CN109858063A - Ship Resistance analogy method based on Unigine - Google Patents
Ship Resistance analogy method based on Unigine Download PDFInfo
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- CN109858063A CN109858063A CN201811392722.0A CN201811392722A CN109858063A CN 109858063 A CN109858063 A CN 109858063A CN 201811392722 A CN201811392722 A CN 201811392722A CN 109858063 A CN109858063 A CN 109858063A
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- 238000000034 method Methods 0.000 title claims abstract description 64
- 238000004088 simulation Methods 0.000 claims abstract description 33
- 239000012530 fluid Substances 0.000 claims abstract description 11
- 230000008676 import Effects 0.000 claims abstract description 4
- 230000008859 change Effects 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 239000013535 sea water Substances 0.000 claims description 2
- 235000013399 edible fruits Nutrition 0.000 claims 1
- 230000008569 process Effects 0.000 description 6
- 230000006870 function Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
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- 238000004134 energy conservation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Abstract
A kind of Ship Resistance analogy method based on Unigine, the method acquires first imports hull characteristics, it generates hull and calculates grid, then Fluid Control Equation is utilized, Numerical Simulation of Turbulent method, turbulence model, Wall-function, free surface analogy method, the direct route resistance and Cross-flow drag of Ship ' at certain speeds, least square method is reused to be fitted obtained numerical result, obtain the corresponding relationship between the speed of a ship or plane and resistance, finally hull is loaded into virtual scene, according to the corresponding relationship between the speed of a ship or plane and resistance, Ship Resistance is calculated by the current speed of a ship or plane, and it brings calculated result into Unigine engine and carries out dynamics feedback, obtain three-dimensional simulation result.The present invention has comprehensively considered the every factor for influencing Ship Resistance, and respective pretreatment is carried out for different ship types, the drag characteristic and posture feature under different hulls, friction speed can not only be gone out with accurate simulation, but also effectively increase frame speed, keep picture more smooth.
Description
Technical field
The present invention relates to a kind of methods of Ship Resistance analog simulation, belong to technical field of data processing.
Background technique
Ship Resistance simulation is the basis that ship driving, cruise are carried out in virtual environment, and establishes accurate ship
Move an important ring for simulation.Currently, resistance model used by ship analogy method under Unigine environment is coarse, only examine
Speed of a ship or plane factor is considered, when ship model parameter modification or sea condition parameter change, ship cannot have been updated according to present case
Kinetic characteristics can not cope with power variation when above-mentioned phenomenon generates, so as to cause the inflexible stiff, traveling of ship power effect
The problems such as larger with turning feature and true ship difference.And since the traditional algorithm under Unigine environment is using calculating in real time
Method, when ships quantity is excessive, it may appear that the problem of frame per second is low, picture Caton, whole simulation is ineffective, can not force
True simulation goes out drag characteristic and posture feature under different hulls, friction speed.
Summary of the invention
It is an object of the invention to aiming at the disadvantages of the prior art, provide a kind of Ship Resistance simulation based on Unigine
Method, with the drag characteristic and posture feature of accurate simulation difference hull at various speeds.
Problem of the present invention is solved with following technical proposals:
A kind of Ship Resistance analogy method based on Unigine, the method acquire first, import hull characteristics, generate
Hull calculate grid, then using preset Fluid Control Equation, Numerical Simulation of Turbulent method, turbulence model, Wall-function, from
By liquid level analogy method, direct route resistance and Cross-flow drag of the Ship ' under specific one group of speed reuse least square method
Obtained numerical result is fitted, to obtain the corresponding relationship between the speed of a ship or plane and resistance, is finally loaded into hull virtual
In scene, according to the corresponding relationship between the speed of a ship or plane and resistance, Ship Resistance is calculated by the current speed of a ship or plane, and calculated result is brought into
Unigine engine carries out dynamics feedback, to obtain three-dimensional simulation result.
The above-mentioned Ship Resistance analogy method based on Unigine uses near hull when generating hull calculating grid
Unstrctured grid uses structured grid in the region far from hull, and only generates hull appearance surface grids when grid generates,
Give up the intracorporal additional grid of ship.
The above-mentioned Ship Resistance analogy method based on Unigine assumes that the flowing of seawater is in the Fluid Control Equation
Potential flows simultaneously ignore heat exchange, it is assumed herein that on the basis of, establish mass-conservation equation and momentum conservation equation.
The above-mentioned Ship Resistance analogy method based on Unigine, the Numerical Simulation of Turbulent method use RANS Numerical-Mode
Quasi- method.
The above-mentioned Ship Resistance analogy method based on Unigine, the turbulence model are solved using SST model.
The above-mentioned Ship Resistance analogy method based on Unigine, in the Wall-function, by empirical equation estimation wall surface the
Its contacting between turbulent core region is established in logarithm layer in the position of one node.
The above-mentioned Ship Resistance analogy method based on Unigine, in the free surface analogy method, using Euler's model
In VOF method, introduce fluid volume and grid cell volume ratio function F to capture the situation of change on the scope of freedom.
The present invention has comprehensively considered the every factor for influencing Ship Resistance, and carries out respective pretreatment for different ship types,
The drag characteristic and posture feature under different hulls, friction speed can not only be gone out with accurate simulation, but also operand is than tradition side
Method substantially reduces, to effectively increase frame speed.It is compared with the traditional method, conventional method frame speed uses this hair in 45.8FPS
It is bright, reach 61.7FPS；Meanwhile picture is also more smooth.
Detailed description of the invention
The invention will be further described with reference to the accompanying drawing.
Fig. 1 is flow diagram of the invention.
Specific embodiment
The present invention uses equipment: 1, the computer of high performance video cards；COMPUTER PARAMETER is as follows:
Processor: Intel (R) Xeon (R) E5-2620v4；Memory: 32GB；Video card: GeForce GTX1080Ti.
The software that the present invention uses: d engine: Unigine, this is a renders comprising vivid three dimensional, with powerful function
The software of energy physical module.
The present invention is to guarantee that simulation is accurate, needs first to pre-process importing ship model, comprising: acquisition hull is special
Sign generates hull and calculates grid, initializes control condition, and CFD operation carries out numerical fitting, pretreatment knot to the speed of a ship or plane and resistance
Shu Hou carries out three-dimensional rendering simulation using Unigine engine.
Preprocessing process: acquisition imports hull characteristics, generates hull and calculates grid, utilizes preset governing equation, turbulent flow
Method for numerical simulation, turbulence model, Wall-function, free surface analogy method use CFD from the microcosmic angle in flow field
Direct route of (Computational Fluid Dynamics, the i.e. computational fluid dynamics) Ship ' under specific one group of speed
Resistance and Cross-flow drag reuse least square method and are fitted to obtained numerical result, thus obtain the speed of a ship or plane and resistance it
Between corresponding relationship.
Unigine simulation process: hull being loaded into virtual scene, the corresponding relationship obtained according to pretreatment stage, is led to
It crosses current airspeed indicator and calculates Ship Resistance, bring Unigine engine into and carry out dynamics feedback, to obtain three-dimensional simulation result.
The mathematical model that analogy method of the present invention uses:
The governing equation of flowing；Governing equation includes: mass-conservation equationConservation of momentum side
Journey:
Following hypothesis: potential flows is made to the flow field around ship, and ignores heat exchange.It is assumed herein that basic
On, establish mass-conservation equation and momentum conservation equation.Due to having ignored heat exchange, therefore energy conservation equation is given up.
Numerical Simulation of Turbulent method: RANS method for numerical simulation is used, compared to DNS and LES method, although RANS gives up
Turbulence pulsation details, but the quantitative description of the turbulent flow characteristic of RANS is enough to this simulation process, and saves
A large amount of computing resource.
Turbulence model: this method is solved using SST model.This models coupling k- ε model and k- ω model it is excellent
Point, uses k- ω model near near wall, and distant place free shear flows use k- ε model.This model being capable of preferable simulation
The flow field of strong adverse pressure gradient reduces the grid dividing requirement near wall, improves computational accuracy.
Wall-function: using wall-function method, by the position of empirical equation estimation first node of wall surface, in logarithm layer
In, its contacting between turbulent core region is established, the grid requirement of near wall is reduced, it can asking to avoid boundary layer
The influence of topic and viscous force.Substantially save the consumption of CPU and memory.
The simulation of free surface: using the VOF method in Euler's model, fluid volume and grid cell volume ratio are introduced
Function F captures the situation of change on the scope of freedom, can preferably handle the scope of freedom and the non-linear phenomenas such as reentry, reduce for mould
The memory consumption of quasi- computer.
Generate hull and calculate grid: the grid dividing of hull is affected to error, therefore this method selection structure/non-structural
Hybrid grid uses unstrctured grid near hull, and the region far from hull uses structured grid.And when grid generates
Hull appearance surface grids are only generated, gives up the intracorporal additional grid of ship, calculating is simplified.
Present invention determine that basic governing equation, Numerical Simulation of Turbulent method, turbulence model, Wall-function, free liquid
After the analogy method of face, CFD drag evaluation is used；CFD drag evaluation includes Fluid Control Equation, turbulence model and the fluid
Mechanical model is calculated, and the corresponding relationship of the speed of a ship or plane and resistance is obtained, so as to accurately simulate ship in three-dimensional scenic
Resistance.Above-mentioned calculating process has comprehensively considered every factor, comprising: ship type feature, water body feature and speed of a ship or plane feature make virtual ship
The posture of oceangoing ship is more accurate.Respective pretreatment is carried out for different ship types, can be gone out under different hulls, friction speed with accurate simulation
Drag characteristic and posture feature, when Fu Rude number is less than 0.3, the error of tank experiment result can be controlled in 15% with
It is interior, and existing technical error is then 20% or so.
By the measure that pretreatment stage is taken, three-dimensional simulation process operand under Unigine is substantially reduced, improved
Frame speed, makes the picture more smooth.By practical comparison it is found that when use tradition real-time computing technique frame speed as 45.8, if adopting
With pretreated resistance simulation method, frame speed be can be improved to 61.7.Using pretreated method, can in Same Scene,
Carry out the real time kinematics simulation of a large amount of ships.
Claims (7)
1. a kind of Ship Resistance analogy method based on Unigine, characterized in that the method acquires first imports hull spy
Sign generates hull and calculates grid, then utilizes preset Fluid Control Equation, Numerical Simulation of Turbulent method, turbulence model, wall surface
Function, free surface analogy method, direct route resistance and Cross-flow drag of the Ship ' under specific one group of speed, reuse minimum
Square law is fitted obtained numerical result, to obtain the corresponding relationship between the speed of a ship or plane and resistance, finally carries hull
Enter in virtual scene, according to the corresponding relationship between the speed of a ship or plane and resistance, Ship Resistance is calculated by the current speed of a ship or plane, and tie calculating
Fruit brings Unigine engine into and carries out dynamics feedback, to obtain three-dimensional simulation result.
2. a kind of Ship Resistance analogy method based on Unigine according to claim 1, characterized in that generate hull
When calculating grid, unstrctured grid is used near hull, the region far from hull uses structured grid, and generates in grid
When only generate hull appearance surface grids, give up the intracorporal additional grid of ship.
3. a kind of Ship Resistance analogy method based on Unigine according to claim 1 or 2, characterized in that the stream
The flowing of seawater is assumed in dynamic governing equation for potential flows and ignores heat exchange, it is assumed herein that on the basis of, establish matter
Measure conservation equation and momentum conservation equation.
4. a kind of Ship Resistance analogy method based on Unigine according to claim 3, characterized in that the turbulent flow
Method for numerical simulation uses RANS method for numerical simulation.
5. a kind of Ship Resistance analogy method based on Unigine according to claim 4, characterized in that the turbulent flow
Model is solved using SST model.
6. a kind of Ship Resistance analogy method based on Unigine according to claim 5, characterized in that the wall surface
In function, it is established between turbulent core region in logarithm layer by the position of empirical equation estimation first node of wall surface
Connection.
7. a kind of Ship Resistance analogy method based on Unigine according to claim 6, characterized in that the freedom
In liquid level analogy method, using the VOF method in Euler's model, introduces fluid volume and caught with grid cell volume ratio function F
Catch the situation of change on the scope of freedom.
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| CN201811392722.0A CN109858063A (en) | 2018-11-21 | 2018-11-21 | Ship Resistance analogy method based on Unigine |
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2018
- 2018-11-21 CN CN201811392722.0A patent/CN109858063A/en active Pending
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| CN101246515A (en) * | 2008-03-03 | 2008-08-20 | 哈尔滨工程大学 | Digital ship model planar motion mechanism experimental method based on CFD software |
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Application publication date: 20190607 |