JPH0763643A - Analyzing apparatus for fluid - Google Patents

Abstract

PURPOSE:To make a solution highly accurate without increasing a conventionally-required calculating time by minimizing a time for controlling a calculating grid in an automatic controlling method for the calculating grid intended to make the solution highly accurate in a fluid analyzing apparatus based on a system of Cartesian coordinates. CONSTITUTION:After a load factor is calculated at a load factor calculating part 3a, a grid distance is algebraically corrected on the basis of each conditional equation of an interval ratio of adjacent grids and an aspect ratio at a grid arrangement calculating part 3b. Accordingly, the arrangement of grids is automatically controlled in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid analysis device in a computer simulation system.

[0002]

2. Description of the Related Art In recent years, due to the dramatic improvement in computer performance, a group of partial differential equations based on the law of physical conservation is analyzed using a plurality of computational grids generated in a large-scale space having complicated boundaries. Computer simulation systems that numerically solve the flow field by iterative calculation by substituting the differential equation for the computational grid generated in space are being widely used. A number of researchers are also studying the calculation method, and one of the research subjects is to calculate the shock wave in the compressible fluid flow around the aircraft with high accuracy and to match the flow pattern of the fluid. A grid control technique for automatically controlling the distribution roughness of has been devised, and is generally called a solution adaptive grid method.

An example of the conventional solution adaptive grid method described above will be described below with reference to the drawings. For example, AIA
A85-1525 P. There is a solution adaptive grid method as shown in 340-350.

FIG. 8 shows a calculation flow of a fluid analysis apparatus to which a conventional solution adaptive grid method is applied. Reference numeral 1 is a physical quantity calculation unit, 2 is a grid control determination unit, 3 is a weight coefficient processing unit, and 4 is a grid reconstruction unit. The arranging unit, 5 is a physical quantity interpolating unit, and 6 is a convergence determining unit.

The operation of the fluid analyzing apparatus configured as described above will be described below. In FIG. 8, first, in order to repeatedly calculate a physical quantity represented by a fluid flow velocity or the like in the physical quantity calculation unit 1, a calculation grid converted into a general coordinate system in advance by (Equation 1) is arranged in the analysis space. .

[0006]

[Equation 1]

Then, the physical quantity calculation unit 1 repeats an appropriate number of iterations, and the grid control determination unit 2 automatically controls the calculation grid when the predetermined iteration count determination value and the number of iterations match. In order to automatically control the grid, the load coefficient processing unit 3 first calculates the load coefficient in each coordinate axis direction while controlling the smoothness and orthogonality of the grid by iterative calculation based on (Equation 2).

[0008]

[Equation 2]

In the equation, W is a weighting coefficient, f is a physical quantity, Δx is a lattice spacing, (n) is the number of iterations, and i and j.
Indicates the grid number. Then, the lattice rearrangement unit 5 calculates the lattice spacing in each coordinate axis direction based on the weighting factor using (Equation 3), and rearranges the lattice.

[0010]

[Equation 3]

L in the equation represents the length of the lattice. After that, the physical quantity is interpolated in the newly arranged grid by some method, and the physical quantity calculation unit 1 is returned to again to continue the calculation of the physical quantity. The lattice control described above is repeated a plurality of times until the convergence determination unit 6 determines that the iterative calculation in the physical quantity calculation unit 1 has converged.

Although various components are actually required for executing the numerical analysis, they are omitted because they are not the main purpose of the present invention.

[0013]

However, in the method as described above, it is necessary to solve a complicated equation by iterative calculation in order to calculate the load coefficient, and the physical quantity calculation in the physical quantity calculation unit is performed every time grid control is performed. Lattice control time as much as the required calculation time is required. Moreover, the effect is not exhibited unless the lattice control is performed a plurality of times until the solution of the converged physical quantity is obtained. Therefore, in order to fully exert the effect of the lattice control, it requires several times as much calculation time as in the case of only calculating the physical quantity, which is not practical in terms of calculation time.

Since the solution adaptive grid method has been studied for a special flow field such as calculation of a shock wave generated in a compressible flow, a grid control method in a general coordinate system has been devised, but an indoor environment analysis is performed. The lattice control method in the Cartesian coordinate system used in, etc. has not been studied.

Further, only a grid control method around a single object has been devised, and a grid control method in an analysis space including a plurality of solid regions has not been devised.

Further, the physical quantity interpolation is considered to have a great influence on the continuity of the physical quantity calculation before and after the grid control by the selection of the method, but the method is not described at all.

Further, the physical quantity calculation process and the grid control process are very inconvenient when viewed as a general-purpose fluid analysis device. For example, when performing unsteady calculation, the flow velocity at a certain time stage. When I try to check the distribution,
It is necessary to pay attention to the matching between the grid and the physical quantity at each grid control step, which may cause an erroneous operation such that the physical quantity at each time step is evaluated based on the grid at a different step.

Further, the physical quantity calculation process and the lattice control process are very inconvenient when viewed as a general-purpose fluid analysis device. For example, when the calculation is temporarily interrupted, If the means for effectively utilizing the information of the physical quantity and the control grid at the time of calculation of is not provided, the calculation efficiency becomes very poor.

In view of the above problems, it is a first object of the present invention to devise a practical grid control method in the Cartesian coordinate system.

A second object is to devise a method of calculating a weighting factor, which is the core of grid control, and to make the grid control method of the present invention more practical and effective.

A third object is to realize grid control when a plurality of solid regions exist in the analysis space in the Cartesian coordinate system.

A fourth object is to converge the physical quantity calculation by continuing the physical quantity calculation without performing the grid control when the grid arrangement movement amount before and after the control is smaller than the predetermined grid arrangement movement amount judgment value. To maintain the property and prevent the increase of calculation time.

A fifth object is to ensure continuity of physical quantity calculation before and after grid control and prevent deterioration of convergence of calculation by devising an appropriate physical quantity interpolation method.

A sixth object is to apply the physical quantity interpolation method used at the time of grid control, interpolate the physical quantity to the initial grid, and then output each physical quantity to the auxiliary storage device of the computer so that the grid and the physical quantity at the time of evaluation of the calculation result are calculated. It is to prevent matching mistakes and improve the usability of the grid control function in the fluid analysis device.

A seventh object is that, when resuming the calculation of the flow field which has been suspended, the physical quantity is interpolated to the previous control grid previously stored in the auxiliary storage device of the computer, and then the control grid is stored in the control grid. By restarting the calculation based on this, the information of the physical quantity and the lattice control in the previous calculation is effectively used.

[0026]

In order to achieve the first object, a fluid analysis device of the present invention is a calculation grid in which a group of partial differential equations based on the law of physical conservation is arranged in an analysis space in a Cartesian coordinate system. A physical quantity calculation unit that replaces the difference equation for the group to obtain a solution of the flow field by iterative calculation, a convergence determination unit that determines whether or not the iterative calculation in the physical quantity calculation unit has converged, and the number of iteration calculation times in the physical quantity calculation unit. Is a grid control determination unit that determines whether or not to control the grid depending on whether or not it matches a plurality of predetermined iteration count determination values, and the basis of the grid control amount based on the physical quantity gradient in each coordinate axis direction. And a grid arrangement calculation unit that corrects the grid spacing calculated from the load coefficient based on the adjacent grid spacing ratio and the aspect ratio of the grid spacing in each coordinate axis direction. A grid relocation unit that relocates the grid based on the grid spacing modified by the grid layout calculation unit, and a grid movement from the grid layout before control to the grid layout after control for each physical quantity being calculated. A physical quantity interpolating unit that performs interpolation corresponding to the amount, wherein the lattice arrangement calculating unit corrects the lattice spacing by algebraically solving conditional expressions for the adjacent lattice spacing ratio and the aspect ratio. It has a configuration. Further, in order to achieve the second object, in the fluid analysis device of the present invention, the load coefficient calculation unit calculates the physical quantity gradient in each coordinate axis direction in each grid, and the unit grid included in a plane perpendicular to each coordinate axis. Based on the maximum value of the physical quantity gradient in the direction perpendicular to the group, the load coefficient of the unit lattice group in the coordinate axis direction perpendicular to the plane is calculated.

In order to achieve the third object, the fluid analysis device of the present invention provides a space sandwiched between the boundary surface between the solid area and the fluid area or the outer boundary surface of the calculation area in the load coefficient calculation unit. As a unit lattice control space, a weighting factor is calculated for each of the unit lattice control spaces, and a lattice arrangement calculation unit adjusts an adjacent lattice spacing ratio at a joint surface of each unit lattice control space. Have

Further, in order to achieve the fourth object, the fluid analysis device of the present invention is such that the grid relocation unit is provided with a grid placement determination unit and the grid placement obtained from the grid placement before grid control by the grid placement calculation unit. When the amount of grid movement to the grid is smaller than a predetermined grid movement amount determination value, the processes in the grid rearrangement unit and the physical quantity interpolation unit after the grid arrangement determination unit are skipped and the physical quantity calculation unit is returned to continue the iterative calculation. It has a configuration characterized in that.

Further, in order to achieve the fifth object, in the fluid analysis device of the present invention, a finite volume is assumed for each grid in the physical quantity interpolating unit, and the grid volume before control occupies in each grid volume after control. The configuration is characterized in that the interpolation amount of each physical quantity is calculated by the ratio.

Further, in order to achieve the sixth object, the fluid analysis device of the present invention stores the physical quantity in the auxiliary storage device of the computer from the grid arrangement state after the control in the physical quantity interpolating unit to the grid arrangement at the initial stage of calculation. It has a configuration characterized by interpolating a physical quantity into a state.

Further, in order to achieve the seventh object, the fluid analysis apparatus of the present invention performs a new calculation based on the physical quantity stored in the auxiliary storage device of the computer from the state where the calculation is temporarily suspended. When resuming, after interpolating the physical quantity from the grid layout at the initial calculation to the grid layout of the final control state at the time of the previous calculation stored in the auxiliary storage device in advance in the physical quantity interpolating unit, The configuration is characterized in that the processing in the physical quantity calculation unit is performed based on the lattice arrangement.

[0032]

With the configuration for achieving the first object, the load coefficient is first calculated based on the existing grid, and then the conditional expressions for the adjacent grid spacing ratio and the aspect ratio of the grid spacing are algebraically solved to obtain the load coefficient or By correcting the lattice spacing, the lattice arrangement in the Cartesian coordinate system can be calculated in a short time.

Further, with the configuration for achieving the second object, the load coefficient in each coordinate axis direction can be calculated effectively and economically.

Further, with the configuration for achieving the third object, it becomes possible to move only the controllable grid without moving the grid expressing the solid boundary existing in the analysis area. Lattice control can be performed economically regardless of the number.

Further, according to the structure for achieving the fourth object, when the lattice arrangement movement amount before and after controlling the lattice is smaller than the predetermined lattice arrangement movement amount judgment value, the lattice control is not performed and the physical quantity is not performed. By continuing the calculation, it is possible to maintain the convergence of the physical quantity calculation and prevent the calculation time from increasing.

Further, with the configuration for achieving the fifth object, the continuity of the physical quantity calculation before and after the lattice control can be secured and the deterioration of the convergence of the calculation can be prevented.

With the configuration for achieving the sixth object, the physical quantity interpolation method used during grid control is applied, the physical quantity is interpolated in the initial grid, and then the physical quantity is output to the auxiliary storage device of the computer to evaluate the calculation result. It is possible to prevent matching errors between the lattice and the physical quantity at the time, and improve the usability of the lattice control function in the fluid analysis device.

Further, with the configuration for achieving the seventh object, when resuming the calculation of the flow field which has been suspended,
By interpolating the physical quantity to the previous control grid stored in the auxiliary storage of the computer in advance and then restarting the calculation based on the control grid, the physical quantity and grid control information in the previous calculations can be effectively used. You can

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of each of the first to seventh inventions will be described below with reference to the drawings. In addition, in order to avoid duplication of description, the same parts as those of the conventional example are denoted by the same reference numerals. Further, in each case, various components for executing the numerical analysis are actually required, but they are omitted because they are not the main object of the present invention.

FIG. 1 shows a configuration and a flow chart of a fluid analysis apparatus according to an embodiment of the first invention. In FIG. 1, 1 is a physical quantity calculation unit, 2 is a lattice control determination unit,
Reference numeral 3a is a weighting factor calculation unit, 3b is a lattice arrangement calculation unit, 4 is a lattice rearrangement unit, 5 is a physical quantity interpolation unit, and 6 is a convergence determination unit.

The operation of the fluid analysis device configured as described above will be described below. First, the physical quantity calculation unit 1
In, the physical equations such as flow velocity and temperature are calculated by iterative calculation by replacing the partial differential equation group based on the law of physical conservation with the difference equation for the calculation grid group arranged in the analysis space in the Cartesian coordinate system. The convergence determination unit 6 repeats the iterative calculation in the physical quantity calculation unit 1 until the residual RS indicating the difference in solution at each stage in the iterative calculation becomes smaller than a predetermined convergence determination value RSLMT. Then, when the predetermined number of iterations determination value NUM in the lattice control determination unit 2 and the number of iterations calculation ISTEP in the physical quantity calculation unit 1 match, lattice control is performed,
If they do not match, the grid control is skipped and the iterative calculation in the physical quantity calculation unit 1 is continued. Number of iteration calculation ISTE
When P coincides with the iteration count determination value NUM, the load coefficient calculation unit 3a first calculates the load coefficient W, which is the basis of the grid control, by (Equation 4).

[0042]

[Equation 4]

In the equation, f is the physical quantity being calculated in the physical quantity calculation unit 1, Δx is the grid spacing, and i and j are the grid numbers in each coordinate axis direction. Next, the lattice arrangement calculation unit 3b
In, the lattice spacing calculated based on the weighting factor W and (Equation 5) is algebraically controlled according to the adjacent lattice spacing ratio and the aspect ratio of each lattice.

[0044]

[Equation 5]

Here, a simple conditional expression shown in (Equation 7) is used to control the adjacent lattice spacing ratio, and a simple conditional expression shown in (Equation 7) is used to control the aspect ratio. The spacing Δx is modified algebraically to calculate a new lattice spacing Δx.

[0046]

[Equation 6]

[0047]

[Equation 7]

As a result, the grid control time can be suppressed to a negligible level as compared with the physical quantity calculation time, and a practical grid control in the Cartesian coordinate system can be realized. Note that 2 in (Equation 6) and 25 in (Equation 7) are empirically set control values for the adjacent lattice spacing ratio and the aspect ratio. After that, the lattice rearrangement unit 4 rearranges the lattice in the analysis space based on the new lattice spacing Δx, and finally the physical quantity interpolating unit 5 interpolates each physical quantity from the old lattice to the new lattice to ensure continuity of physical quantity calculation. After that, the process returns to the physical quantity calculation unit 1.

In this embodiment, the physical quantity used in (Equation 4) for calculating the load coefficient is not particularly mentioned, but the physical quantity to be used may be the flow velocity or the pressure directly. Alternatively, a synthetic function or the like of each physical quantity may be used. Further, although the physical quantity interpolation unit 5 is provided after the lattice rearrangement unit 4, whichever comes first may be used. Further, 2 in (Equation 6) and 25 in (Equation 7) are empirical parameters and can be arbitrarily determined.

Next, FIG. 2 is an explanatory diagram of a load coefficient calculation method in an embodiment of the second invention. In FIG. 2, W is a load coefficient, i is a grid number in the X direction in the Cartesian coordinate system, and j is a grid number in the Y direction.

The method of calculating the weighting factor in one embodiment constructed as described above will be described in two dimensions for simplicity.

The weighting factor W is calculated based on the physical quantity gradient in each coordinate axis direction using (Equation 4) in each lattice. In the Cartesian coordinate system, the lattice group of (Equation 8) existing on the i-th lattice line is calculated. Since the X-direction movement amount is uniquely determined, the load coefficient W can be represented by the representative value of the grid point group on the i-th grid line.

[0053]

[Equation 8]

Therefore, by using the maximum value of the weighting factor W as a representative value according to (Equation 9), a new grid interval Δx can be calculated based on the most severe physical quantity gradient on the i-th grid line. The grid can be concentrated in the part where the change is drastic, and the grid can be arranged roughly in the part where the change is gentle, and the physical quantity gradient can be evenly distributed in the analysis space in each grid, improving the accuracy of the solution of the physical quantity. Can be planned.

[0055]

[Equation 9]

Although the present embodiment has been described in two dimensions for simplification, the present embodiment can be expanded to three dimensions as it is.

FIG. 3 is an explanatory diagram of the grid control method in the embodiment of the third invention. In FIG. 3, a region surrounded by a solid line or a dotted line represented by L ₁ and L ₂ is a space formed by the boundary between the solid region and the fluid region or the outer boundary of the analysis region, and indicates the unit space width of the grid control. ing.

The lattice control method according to the embodiment having the above-described configuration will be described below in two dimensions for simplicity.

According to the embodiment of the first invention, L ₁ and L ₂
After calculating the new grid spacing for each unit space shown in
Even if there are a plurality of solid regions in the analysis space in the Cartesian coordinate system, the solid boundaries can be corrected by correcting again the adjacent lattice spacings that sandwich the boundary of each unit space by using (Equation 6) and (Equation 7). Without moving the grid line representing
Lattice control can be performed.

Although the present embodiment has been described in two dimensions for the sake of simplicity, the present embodiment can be extended to three dimensions as it is.

Further, FIG. 4 shows a structure and a flow chart of a fluid analysis apparatus in one embodiment of the fourth invention.

In FIG. 4, reference numeral 4a denotes a lattice arrangement determining unit provided in the lattice rearranging unit 4, and 4b denotes a lattice arrangement executing unit.

The operation of the fluid analyzing apparatus in one embodiment constructed as above will be described below.

When the lattice movement amount D of the lattice arrangement with respect to the old lattice arrangement calculated by the embodiment of the first invention or the like is smaller than the predetermined lattice movement amount judgment value DELTA, the lattice arrangement execution unit 4b and the physical quantity. The calculation unit 5 is skipped, the process returns to the physical quantity calculation unit 1, and when the lattice movement amount D is equal to or larger than the lattice movement amount determination value DELTA, the lattice arrangement execution unit 4b rearranges the lattice and then the physical amount interpolation unit 5 The physical quantity is interpolated to a new grid layout by returning to the physical quantity calculation unit 1, and when the grid hardly moves, the grid layout execution unit 4b and the physical quantity interpolation unit 5 are skipped, and the physical quantity calculation unit 1 repeats the physical quantity. It is possible to prevent the convergence of the calculation from being hindered, and as a result, it is possible to prevent the total calculation time from being carelessly increased and to improve the efficiency of the lattice control.

FIG. 5 is an explanatory diagram of a physical quantity interpolation method in an embodiment of the fifth invention. In FIG. 5, abc
d represents the representative value of the physical quantity in the area area surrounded by the old grid line that spatially overlaps with the area surrounded by the control grid line, and X ₁ X ₂ Y ₁ Y ₂ is the value after the control. The distance between the old grid line between the grid lines and the new grid line after control is shown.

The physical quantity interpolation method in one embodiment configured as described above will be described two-dimensionally for simplicity.

When the physical quantity is interpolated, the representative value of the physical quantity of each old area is interpolated to the new grid by (Equation 10) based on the area ratio of the area surrounded by the new grid line to the area surrounded by the new grid line. As a result, the grid control can be performed without losing the spatial meaning of the physical quantity, and the physical quantity calculation can be continued before and after the grid control without impairing the continuity of the iterative calculation in the physical quantity calculation unit 1. Lattice control can be performed without increasing the overall size.

[0068]

[Equation 10]

Here, φ in (Equation 10) indicates a physical quantity after interpolation. It should be noted that although the present embodiment has been described in two dimensions for simplicity, it goes without saying that the present embodiment can be extended to volume interpolation in three dimensions.

FIG. 6 is a diagram for explaining the operation of the embodiment of the sixth invention. In FIG. 6, reference numeral 5a denotes a physical quantity interpolating unit added to the configuration diagram of the embodiment in FIG. 1 or FIG. 4, and 7 denotes a physical quantity file after being interpolated from the control grid output to the auxiliary storage device of the computer to the initial grid. There is.

The operation of the fluid analyzing apparatus in one embodiment constructed as above will be described below.

When the calculation result of the physical quantity calculated by the physical quantity calculation unit 1 is output to the auxiliary storage device, the physical quantity calculation unit 5a interpolates the physical quantity from the final control grid to the grid at the initial calculation time to evaluate the calculation result. Since only one grid can be used, it is possible to prevent a matching error between a plurality of control grids and the calculation result when the calculation result is evaluated, and improve the usability of the entire fluid analysis device.

FIG. 7 is an operation explanatory diagram in the embodiment of the seventh invention. In FIG. 7, 5b is a physical quantity interpolating unit added at the beginning of the configuration diagram of one embodiment in FIG. 1 or 4, and 8 is a file storing information on the lattice arrangement at the final control stage in the previous calculation.

The operation of the fluid analyzing apparatus according to the embodiment constructed as above will be described below.

When the calculation in the fluid analysis device is temporarily stopped and the calculation is restarted based on the previous calculation result, the data is stored in the auxiliary storage device of the computer in advance from the initial grid at the end of the previous calculation. After the physical quantity 7 is interpolated in the control grid 8 that has been set aside, by continuing the physical quantity calculation in the physical quantity calculation unit 1 based on the control grid 8, the calculation result of the physical quantity and the control grid in the previous calculation are effectively utilized, It is possible to efficiently proceed with the whole calculation until the final result of the physical quantity is obtained.

[0076]

As described above, according to the present invention, the partial differential equation group based on the law of physical conservation is replaced with the difference equation for the calculation grid group arranged in the analysis space in the Cartesian coordinate system, and the flow field of the flow field is calculated by iterative calculation. A physical quantity calculation unit that obtains a solution, a convergence determination unit that determines whether or not iterative calculations in the physical quantity calculation unit have converged, and the number of iteration calculations in the physical quantity calculation unit matches a plurality of predetermined iteration count determination values. Adjacent to the grid control determination unit that determines whether or not to control the grid depending on whether to perform, and a load coefficient calculation unit that calculates the load coefficient that is the basis of the grid control amount based on the physical quantity gradient in each coordinate axis direction, A lattice arrangement calculation unit that corrects the lattice spacing calculated from the load coefficient based on the lattice spacing ratio and the aspect ratio of the lattice spacing in each coordinate axis direction; A grid relocation unit that relocates the grid based on the child spacing, and a physical quantity interpolator that interpolates the calculated physical quantity to the grid movement amount from the grid layout before control to the grid layout after control. In the lattice arrangement calculation unit, the lattice spacing is corrected by algebraically solving the conditional expressions for the adjacent lattice spacing ratio and the aspect ratio, thereby making it practical in the Cartesian coordinate system. Lattice control can be realized.

Further, in the load coefficient calculation section, the physical quantity gradient in each coordinate axis direction in each grid is calculated, and based on the maximum value of the physical quantity gradient in the direction perpendicular to the unit lattice group included in the plane perpendicular to each coordinate axis. By calculating the weighting factor of the unit lattice group in the coordinate axis direction perpendicular to the plane, the lattice control in the Cartesian coordinate system can be performed more practically and economically.

Further, the space sandwiched between the boundary surface between the solid region and the fluid region or the outer boundary surface of the calculation region in the load coefficient calculation unit is set as a unit grid control space, and the load coefficient is set for each unit grid control space. A plurality of solid regions exist in the analysis space in the Cartesian coordinate system by calculating and adjusting the adjacent lattice spacing ratio at the joint surface of each unit lattice control space in the lattice arrangement calculation unit. In this case, grid control can be realized.

Furthermore, the grid relocation unit is provided with a grid placement determination unit, and the grid movement amount from the grid placement before the grid control to the grid placement obtained by the grid placement calculation unit is greater than the predetermined grid movement amount determination value. When the size is small, the processes in the grid rearrangement unit and the physical quantity interpolation unit after the grid layout determination unit are skipped, the process is returned to the physical quantity calculation unit, and the iterative calculation is continued. If the placement movement amount is smaller than the predetermined grid placement movement amount judgment value, the physical quantity calculation can be continued without performing grid control, and as a result, the convergence of the physical quantity calculation can be maintained and an increase in calculation time can be prevented. You can do it.

Furthermore, the physical quantity interpolating unit is characterized in that a finite volume is assumed for each grid and the interpolation quantity of each physical quantity is calculated from the ratio of the grid volume before control to each grid volume after control. As a result, the continuity of the physical quantity calculation before and after the grid control can be ensured and the deterioration of the convergence can be prevented.

Further, when the physical quantity is stored in the auxiliary storage device of the computer, the physical quantity interpolating unit interpolates the physical quantity from the lattice arrangement state after control to the lattice arrangement state at the initial calculation stage, thereby obtaining the calculation result. Mismatch between the lattice and the physical quantity at the time of evaluation can be prevented, and the usability of the lattice control function in the fluid analysis device can be improved.

Further, when the calculation is restarted from the state in which the calculation was temporarily suspended based on the physical quantity stored in the auxiliary storage device of the computer, the physical quantity interpolating unit starts from the grid layout in the initial calculation. After the physical quantity is interpolated to the grid layout of the final control state in the previous calculation stored in the auxiliary storage device, the physical quantity calculation unit performs processing based on the grid layout of the final control state. By doing so, it is possible to effectively utilize the information of the physical quantity and the lattice control in the calculation before that.

[Brief description of drawings]

FIG. 1 is a configuration and flowchart of a fluid analysis device according to an embodiment of the first invention.

FIG. 2 is an explanatory diagram of a load coefficient calculation method in an embodiment of the second invention.

FIG. 3 is an explanatory diagram of a lattice control method according to an embodiment of the third invention.

FIG. 4 is a configuration and flowchart of a fluid analysis device according to an embodiment of the fourth invention.

FIG. 5 is an explanatory diagram of a physical quantity interpolation method according to an embodiment of the fifth invention.

FIG. 6 is an operation explanatory diagram in the embodiment of the sixth invention.

FIG. 7 is an operation explanatory diagram in an embodiment of the seventh invention.

FIG. 8 is a configuration and flowchart of a conventional fluid analysis device.

[Explanation of symbols]

 2 Lattice control determination unit 3a Load coefficient calculation unit 3b Lattice arrangement calculation unit 4 Lattice rearrangement unit 5 Physical quantity calculation unit

Claims (7)

[Claims] 1. A physical quantity calculation unit for replacing a partial differential equation group based on the law of physical conservation with a differential equation for a calculation grid group arranged in an analysis space in the Cartesian coordinate system to obtain a solution of a flow field by iterative calculation. Convergence determination unit that determines whether or not the iterative calculation in the physical quantity calculation unit has converged, and control of the lattice by whether or not the number of iteration calculations in the physical quantity calculation unit matches a plurality of predetermined iteration number determination values. Grid control determination unit that determines whether or not to perform, a load coefficient calculation unit that calculates the load factor that is the basis of the grid control amount based on the physical quantity gradient in each coordinate axis direction, the adjacent grid spacing ratio and each coordinate axis direction A grid layout calculation unit that modifies the grid spacing calculated from the weighting factor based on the aspect ratio of the grid spacing, and a grid layout based on the grid spacing modified by the grid layout calculation unit. And a physical quantity interpolating section for interpolating a physical quantity being calculated, the physical quantity interpolating section corresponding to the amount of grid movement from the pre-control grid layout to the post-control grid layout for each physical quantity being calculated. In the section, the fluid analysis device is characterized in that the lattice spacing is corrected by algebraically solving the conditional expressions for the adjacent lattice spacing ratio and the aspect ratio. 2. A load factor calculation unit calculates a physical quantity gradient in each coordinate axis direction in each grid, and based on a maximum value of a physical quantity gradient in a direction perpendicular to a unit lattice group included in a plane perpendicular to each coordinate axis. The fluid analysis device according to claim 1, wherein a load coefficient of the unit lattice group in a coordinate axis direction perpendicular to the plane is calculated. 3. A unit grid control space is defined as a space sandwiched between a boundary surface between a solid region and a fluid region or an outer boundary surface of the calculation region in the load coefficient calculation unit, and a load coefficient is set for each unit grid control space. The fluid analysis device according to claim 1 or 2, wherein the calculation is performed and the adjacent lattice spacing ratio on the joint surface of each unit lattice control space is adjusted by the lattice arrangement calculation unit. 4. The grid relocation unit is provided with a grid placement determination unit, and the grid movement amount from the grid placement before grid control to the grid placement obtained by the grid placement calculation unit is greater than a predetermined grid movement amount determination value. The fluid analysis according to claim 1 or 2 or 3, wherein when it is smaller, the processes in the lattice rearrangement unit and the physical quantity interpolation unit after the lattice arrangement determination unit are skipped, the process is returned to the physical amount calculation unit, and the iterative calculation is continued. apparatus. 5. A physical quantity interpolating unit, wherein a finite volume is assumed for each grid, and the interpolation quantity of each physical quantity is calculated by the ratio of the lattice volume before control to each lattice volume after control. Item 5. The fluid analysis device according to item 1 or 2 or 3 or 4. 6. The physical quantity is interpolated from a lattice arrangement state after control to a lattice arrangement state at an initial stage of calculation when the physical quantity is stored in the auxiliary storage device of the computer. Alternatively, the fluid analysis device according to 3 or 4 or 5. 7. When restarting the calculation based on the physical quantity stored in the auxiliary storage device of the computer from the state where the calculation is temporarily interrupted, the physical quantity interpolating unit preliminarily changes the grid layout from the initial calculation. After the physical quantity is interpolated to the grid arrangement in the final control state at the time of the previous calculation stored in the auxiliary storage device, the physical quantity calculation unit performs processing based on the grid arrangement in the final control state. The fluid analysis device according to claim 6.