JP2005339350A - Hot fluid simulation device, hot fluid simulation method, hot fluid simulation program, and recording medium with the program recorded thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot fluid simulation method capable of shortening the calculation time of simulation calculation and performing simulation calculation for an object moving with deformation. <P>SOLUTION: A calculation condition used for simulation calculation is determined (s1), and a flow field and a temperature field in an initial state are simulation-calculated by use of the determined calculation condition (s2). It is determined whether n-step reaches a predetermined step number N or not, and when it does not reach, the step is advanced to (n+1) step (s3 and s4). The analysis result of simulation calculation is set as an initial value of simulation calculation in the (n+1) step (s5), and the flow field and temperature field in the (n+1) step are simulation-calculated based on the set initial value (s6). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the field of engineering simulation, and relates to a thermofluid simulation apparatus, a thermofluid simulation method, a thermofluid simulation program, and a recording medium recording the thermofluid simulation program in a system including a moving object.

  Conventionally, in a thermofluid simulation in which a moving object and a flow field and a temperature field around the moving object are simulated in a system including a rotating or linearly moving object, a single calculation mesh (hereinafter, simply referred to as an object) is represented. A method is used in which a mesh is recreated at each calculation step accompanying the movement of an object.

  FIG. 5 is a diagram for explaining a conventional thermal fluid simulation method. FIG. 5 illustrates an example in which an object 1 having a circular planar shape rotates and uses a rotationally moving object 1 and a single mesh formed around the object 1. In the example of FIG. 5, the outside of the boundary 2 that separates the rotationally moving object 1 from the outside is gas. The mesh is formed so as to extend to the rotating moving object 1 and its surroundings, and an element number for identifying each element is assigned to each element constituting the mesh. In FIG. 5, the element number is represented by a circled number. Although element numbers are assigned to all individual elements constituting the mesh, only element numbers 1 to 12 are displayed in FIG. 5 to avoid complication.

  In general, in the thermal fluid simulation, a time series simulation is performed in which a certain time step is set and calculation is performed at each step. FIG. 5 also shows a time series simulation. FIG. 5A shows the state at a certain time step n, and FIG. 5B shows the next time step n + 1 after a predetermined time has elapsed from the time of FIG. The state in is shown.

  The predetermined time in the example of FIG. 5 is the time required for the rotationally moving object 1 to rotate and move by one mesh component in the clockwise direction indicated by the arrow 3. Therefore, when a predetermined time has elapsed and the state of FIG. 5A is shifted to the state of FIG. 5B, that is, when one calculation step is performed, only the mesh formed on the rotationally moving object 1 is obtained. Becomes a mesh shifted clockwise by one element. This means that this is a new mesh in which the connection state between each element changes, and for simulation calculation, it is necessary to create a new mesh and solve a new equation corresponding thereto.

  Therefore, the conventional method has a problem that a large amount of calculation is required because a balance equation representing a mesh, that is, a state must be recreated at each step of the simulation calculation.

  Another conventional technology of thermal fluid simulation uses multiple meshes, moves the mesh around the moving object independently of the other meshes, and flows at the connection boundary nodes of each mesh system at each calculation step. There is a simulation method to calculate while exchanging field information. However, in this prior art, it takes a lot of calculation time to search for mesh cells (elements) of other meshes to which the connection boundary node belongs, which is necessary when each mesh exchanges flow field information at the connection boundary node. There is a problem that the amount of calculation increases due to the movement of the object.

  In a conventional technique for solving such a problem, in a new calculation step, a search for the mesh cell number of the other mesh to which the connection boundary node of one mesh belongs is performed in advance, and a table referring to adjacent mesh cells in each mesh system is previously stored. There is one that is created and exchanged from the mesh cell to which the connection boundary node belongs in the previous calculation step and its adjacent mesh cell, and exchanges flow field information (see Patent Document 1).

  In the technique disclosed in Patent Document 1, the time required for searching for mesh cells can be shortened. However, in each new mesh including the searched mesh cells, a balance equation representing a state is created each time. Therefore, there remains a problem that the amount of calculation for solving the above problem is necessary, so that the reduction of the amount of calculation and the reduction of the calculation time are not yet achieved sufficiently.

  In the above-described conventional technology, the object is a rigid body that does not deform, and simulation is possible in the case of rotation or linear movement, but it is applied when the object moves while deforming like a rubber belt, for example. There is a problem that you can not.

JP-A-4-319767

  An object of the present invention is to provide a thermal fluid simulation apparatus and a thermal fluid simulation method that can shorten the calculation time of the simulation calculation and also enable the simulation calculation for an object that moves while being deformed.

  Another object of the present invention is to provide a thermal fluid simulation program for a computer to execute the thermal fluid simulation method and a computer-readable recording medium on which the thermal fluid simulation program is recorded.

The present invention relates to a thermal fluid simulation apparatus for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in plural in a system including the moving object,
Calculation condition supply means for supplying calculation conditions used for simulation calculation;
The calculation conditions supplied from the calculation condition supply means are used to perform a simulation calculation of the moving object and the flow field and temperature field in the initial state around the object, and in steps other than the initial state, based on the initial values given for each step. A calculation means for simulating a moving object and a flow field and a temperature field around the moving object;
Analyzing the simulation calculation result by the calculation means, and providing the analysis result to the calculation means as an initial value of the simulation calculation in the next step;
A thermal fluid simulation apparatus comprising: calculation condition supply means, calculation means, and control means for controlling the operation of the analysis result moving means.

Further, the present invention relates to a thermofluid simulation method for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Analyzing the simulation calculation result, and setting the analysis result as an initial value of the simulation calculation in the next step;
A thermal fluid simulation method comprising a simulation calculation of a moving object and a flow field and a temperature field around the moving object based on a set initial value.

The present invention also relates to a thermal fluid simulation program used for simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in plural in a system including the moving object. There,
at least,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Analyzing the simulation calculation result, and setting the analysis result as an initial value of the simulation calculation in the next step;
A thermal fluid simulation program for causing a computer to execute a simulation calculation of a moving object and a flow field and a temperature field around the object based on a set initial value.

  The present invention is also a computer-readable recording medium on which the thermal fluid simulation program is recorded.

  According to the present invention, simulation calculation is performed on a moving object and a flow field and a temperature field around the object in an arbitrary calculation step, the simulation calculation result is analyzed, and the analysis result is set as an initial value of the simulation calculation in the next step. In the next step, the moving object and the flow field and temperature field around the object are simulated based on the set initial value, so it is not necessary to recreate the balance equation in each step of the simulation calculation, and the calculation time can be shortened. Can be realized. In addition, it is possible to perform a thermal fluid simulation of a system including an object that moves while being deformed, such as a rubber belt.

  According to the present invention, there is provided a thermal fluid simulation method in which a simulation calculation result in an arbitrary calculation step is used as an initial value of the simulation calculation in the next step as a thermal fluid simulation program executed by a computer. Is provided as a computer-readable recording medium on which is recorded. Therefore, the versatility of the thermal fluid simulation method is increased, and the thermal fluid simulation method can be easily executed in a short time by a computer.

  FIG. 1 is a block diagram showing a simplified configuration of a thermal fluid simulation apparatus 10 according to an embodiment of the present invention. The thermal fluid simulation apparatus 10 is roughly calculated by a calculation condition supply means 11 for supplying calculation conditions used for simulation calculation, and a moving object and an initial state around the object using the calculation conditions supplied from the calculation condition supply means 11. And a calculation means 12 for performing a simulation calculation of the flow field and the temperature field of the moving object and performing a simulation calculation of the flow field and the temperature field around the moving object based on the initial values given for each step in steps other than the initial state, An analysis result moving unit 13 that analyzes the simulation calculation result by the unit 12 and gives the analysis result to the calculation unit 12 as an initial value of the simulation calculation in the next step, a calculation condition supply unit 11, a calculation unit 12, and an analysis result movement unit 13 Control means 14 for controlling the operation of the Configured to include a display unit 15 for displaying the Shon calculation results.

  The thermal fluid simulation apparatus 10 is used for simulation calculation for each step of a step in which a moving object, a flow field around the object, and a temperature field are set in plural in a system including a moving object.

  In the present embodiment, the calculation condition supply means 11 has a shape data storage unit 21 in which data relating to the shape and mesh of the moving object is stored in advance, and physical property data relating to the moving object and fluid around the moving object are stored in advance. Calculation condition data storage in which calculation condition data such as boundary conditions, heat generation conditions, time intervals for repeatedly executing simulation calculations, and the number of steps, which is the number of times the simulation calculations should be repeated, are stored in advance. Unit 23 and a manual input data unit 24 that can manually input each of the above data.

  The shape data storage unit 21, the physical property data storage unit 22, and the calculation condition data storage unit 23 are memory devices realized by, for example, a random access memory (RAM) or a hard disk drive (HDD). Data stored in each of the shape data storage unit 21, the physical property data storage unit 22, and the calculation condition data storage unit 23 may be given from another computer, for example, or may be input from the manual input unit 24.

  The manual input unit 24 is an input device such as a keyboard. Each of the above-mentioned data may be directly input to the calculation means 12 from the manual input unit 24 according to the simulation calculation opportunity. In addition, the shape data storage unit 21, the physical property data storage unit 22, the calculation conditions are previously input from the manual input unit 24. The data may be input to each unit of the data storage unit 23 and read from each unit according to the simulation calculation opportunity.

  The calculation means 12 is an arithmetic circuit realized by, for example, a large-scale integrated circuit (LSI). In this embodiment, the flow field calculation unit 25 that calculates the flow field and the temperature field calculation unit that calculates the temperature field. 26. The calculation means 12 outputs the result of the simulation calculation of the initial state and the flow field and the temperature field at n steps, which are arbitrary steps, to the analysis result moving means 13.

  The analysis result moving means (analysis result moving unit) 13 is an arithmetic circuit realized by an LSI or the like, and includes a memory unit 13a. An analysis result moving program is stored in the memory unit 13a in advance. When the n-step simulation calculation result is given from the calculation means 12, the analysis result moving means 13 reads the analysis result moving program from the memory unit 13a, and according to the program, the calculation result is expressed as “object moving speed × step time. Is moved as much as the amount of movement of the object in one step calculated in step (1), and this is set as an initial value used for the simulation calculation in the next n + 1 step and output to the calculation means 12. When the initial value is given from the analysis result moving means 13, the calculating means 12 executes n + 1 step simulation calculation.

  The control means (control unit) 14 is a processing circuit including, for example, a central processing unit (abbreviated as CPU). Although not shown, the control unit 14 includes a storage unit that stores in advance a program for controlling the overall operation of the thermal fluid simulation apparatus 10. The storage unit is realized by, for example, a read only memory (ROM). The control unit 14 controls the operations of the calculation condition supply unit 11, the calculation unit 12, and the analysis result moving unit 13 according to the program read from the storage unit. In the present embodiment, the control means 14 is formed integrally with the calculation means 12 and the analysis result moving means 13.

  The display means (display unit) 15 is a display device having a screen capable of displaying an image, such as a cathode ray tube (CRT) or a liquid crystal display (LCD). The display means 15 may be provided with a printer or the like for recording the thermal fluid simulation calculation result on recording paper or the like.

  FIG. 2 is a flowchart for explaining a thermal fluid simulation method performed using the thermal fluid simulation apparatus 10 shown in FIG. The operation of the control means 14 relating to the execution of the thermal fluid simulation method will be described with reference to FIG. In many cases, the thermal fluid simulation is performed on a three-dimensional space, but here, in order to facilitate the description, a case of a two-dimensional space will be described. The principle and effect of the simulation are the same regardless of whether they are two-dimensional or three-dimensional.

  At the start of the procedure s0, each switch of the thermal fluid simulation device 10 is turned on and can be operated. Each data is stored.

  In the procedure s1, various conditions necessary for the simulation calculation of the thermal fluid, that is, the simulation calculation of the flow field and the temperature field are the shape data storage unit 21, the physical property data storage unit 22 and the calculation condition data storage unit which are the calculation condition supply means 11. 23. In the thermal fluid simulation method illustrated in FIG. 2, N is the number of steps that is the number of simulation calculation iterations.

  In step s2, the flow field and temperature field simulation calculation in the initial state, that is, step n = 0 is performed using the read calculation condition, and the field balance result in the initial state is calculated. Here, for example, a known Navier Stokes equation can be used for the calculation of the flow field, and a known Poisson equation can be used for the calculation of the temperature field.

  In step s3, it is determined whether or not to end the simulation calculation, that is, whether or not n indicating the step (number of field calculations) currently being executed has reached the number of steps N read in step s1. To be judged. This determination is also made by the control means 14. If the determination result is negative and n has not reached N, the process proceeds to step s4. If the determination result is affirmative, and n has reached N, the process proceeds to the end of step s7, and the simulation calculation is terminated.

  In step s4, the value of n is replaced with (n + 1) obtained by adding one, and the process proceeds to step s5. In step s5, the simulation result is output from the calculation means 12 to the analysis result moving means 13, and the analysis result moving means 13 slides the simulation calculation result by the amount of object movement in one step, and the initial simulation calculation is performed. Set as a value.

  The operation in step s5 will be further described with reference to FIG. FIG. 3 is a diagram for explaining the movement of the analysis result. FIG. 3A shows a simulation calculation result in n steps, and FIG. 3B shows a condition setting for simulation calculation in (n + 1) steps. FIG. 3 illustrates a case where an object 31 having a circular planar shape rotates in gas. Therefore, the outside of the boundary 32 that separates the rotationally moving object 31 from the outside is gas. The mesh is formed so as to extend to and around the rotationally moving object 31, and an element number for identifying each element is assigned to each element constituting the mesh. In FIG. 3, the element number is represented by a circled number. Although element numbers are assigned to all individual elements constituting the mesh, only element numbers 1 to 12 are displayed in FIG. 3 to avoid complication. In addition, the simulation calculation result in n steps is shown by further enclosing R + circled numbers with squares.

  In order to calculate the state at the next (n + 1) step, the balance equation must be solved in consideration of the effect of the rotating moving object 31 rotating. Since the rotationally moving object 31 is circular and does not change in shape when rotated in the direction of the arrow 33, if the element number of the mesh is reassigned, it can be made the same as the mesh in n steps.

  Therefore, instead of sliding the mesh formed on the rotationally moving object 31 in the direction of the arrow 33, the simulation calculation result executed in n steps for each element constituting the mesh formed on the rotationally moving object 31 is obtained. The simulation calculation result that is rotated by one element in the direction of the arrow 33 and positioned in each element after the rotation is set as the initial value of the simulation calculation in the (n + 1) step. FIG. 3B shows a state in which the simulation calculation result at the n step is shifted by one element of the mesh in the direction of the arrow 33 in order to execute the simulation calculation at the (n + 1) step.

  FIG. 3 illustrates the case where the amount of movement of the object in one step and the distance between the element centers are equal for ease of explanation, but if the amount of movement of the object in one step and the distance between the element centers do not match, A similar effect can be obtained by performing linear interpolation according to the positional deviation distance from the center.

  In step s6, an initial value is output from the analysis result moving unit 13 to the calculating unit 12, and the calculating unit 12 performs a simulation calculation regarding the balance between the flow field and the temperature field using the initial value, and returns to step s3. . After step s3, the above-described operation is repeated, and when n reaches N, a series of thermal fluid simulations is completed.

  As described above, according to the thermal fluid simulation method of the present invention, simulation calculation can be performed without moving the mesh, so that it is not necessary to regenerate the balance equation in each calculation step, and the calculation time is remarkably shortened. Can do.

  FIG. 4 is a diagram illustrating a thermal fluid simulation method for an object that moves while deforming. FIG. 4 illustrates a belt 43 that is wound around a drive pulley 41 and a driven pulley 42 and moves. The belt 43 is made of an elastic body such as rubber, and the driving pulley 41 is driven to rotate in the direction of the arrow 44 by an electric motor (not shown), the rotational driving force is transmitted to the belt 43, and the belt 43 is deformed while being deformed. Move in the direction of 45. According to the present invention, it is possible to simulate an object that moves with deformation, such as the belt 43 shown in FIG.

  Similarly to the above, the element numbers constituting the mesh are represented by circled numbers, and the simulation calculation results in n steps are represented by further enclosing R + circled numbers with squares. In a system including a moving object with deformation such as the belt 43 shown in FIG. 4, according to the method of moving the mesh itself, the belt 43 linearly rotates and the belt 43 rotates along the outer periphery of the pulleys 41 and 42. Since the shape of the mesh changes with the portion, it cannot be simulated. However, as in the present invention, the influence of the movement of the belt 43 is changed to the next simulation by moving only the simulation result along the moving path of the belt 43 as the calculation step proceeds without changing the mesh itself. Since it can be reflected in the calculation step, simulation in a system including a moving object with deformation becomes possible.

  The present invention also provides a thermal fluid simulation program for causing a computer to operate as a thermal fluid simulation apparatus, and a computer-readable recording medium recording the thermal fluid simulation program.

  As a recording medium for recording the thermal fluid simulation program, for example, a ROM or the like provided in the control unit 14 described above can be cited. Further, the recording medium may be a medium that is provided with a program reading device as an external device and is inserted into the reading device to be read.

  When an externally read type recording medium is used in the thermal fluid simulation apparatus 10, a thermal fluid simulation program is read from the recording medium by the reading apparatus, and the read thermal fluid simulation program is not included in the control means 14. The program is downloaded to the illustrated program storage unit and executed. It is assumed that the download program is stored in advance in the storage unit of the control unit 14.

Recording media that can be read by a reader include magnetic tapes such as cassette tapes, magnetic disks such as flexible disks, compact disks (CDs), digital versatile disks (DVDs), mini disks (MDs), magneto optical disks (MOs). ) And other optical or magneto-optical recording media, integral circuit (IC) cards (including memory cards), optical cards, mask ROMs that carry a fixed program including semiconductor memory,
Erasable Programmable Read Only Memory (EPROM), Electrically Erasable
Programmable Read Only Memory (EEPROM), flash ROM, etc. are mentioned.

It is a block diagram which simplifies and shows the structure of the thermal fluid simulation apparatus 10 which is one Embodiment of this invention. It is a flowchart explaining the thermal fluid simulation method performed using the thermal fluid simulation apparatus 10 shown in FIG. It is a figure explaining the movement of an analysis result. It is a figure explaining the thermal fluid simulation method about the object which moves while deform | transforming. It is a figure explaining the conventional thermal fluid simulation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Thermo-fluid simulation apparatus 11 Calculation condition supply means 12 Calculation means 13 Analysis result moving means 14 Control means 15 Display means 21 Shape data storage part 22 Physical property data storage part 23 Calculation condition data storage part 24 Manual input part 25 Flow field calculation part 26 Temperature field calculator

Claims (4)

In a thermal fluid simulation apparatus for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object,
Calculation condition supply means for supplying calculation conditions used for simulation calculation;
The calculation conditions supplied from the calculation condition supply means are used to perform a simulation calculation of the moving object and the flow field and temperature field in the initial state around the object, and in steps other than the initial state, based on the initial values given for each step. A calculation means for simulating a moving object and a flow field and a temperature field around the moving object;
Analyzing the simulation calculation result by the calculation means, and providing the analysis result to the calculation means as an initial value of the simulation calculation in the next step;
A thermal fluid simulation apparatus comprising: calculation condition supply means, calculation means, and control means for controlling the operation of the analysis result moving means. In a thermal fluid simulation method for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Analyzing the simulation calculation result, and setting the analysis result as an initial value of the simulation calculation in the next step;
A thermal fluid simulation method comprising: a simulation calculation of a moving object and a flow field and a temperature field around the moving object based on a set initial value. A thermal fluid simulation program used for simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including a moving object,
at least,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Analyzing the simulation calculation result, and setting the analysis result as an initial value of the simulation calculation in the next step;
A thermal fluid simulation program for causing a computer to execute a simulation calculation of a moving object and a flow field and a temperature field around the object based on a set initial value.   A computer-readable recording medium on which the thermal fluid simulation program according to claim 3 is recorded.

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