摘要：

      艦船自航評(píng)估和研究通常是由拖曳水池自航試驗(yàn)實(shí)現(xiàn)，實(shí)施周期長(zhǎng)，耗資大。船舶三維多面體OPENFOAM

潛艇外流場(chǎng)分析報(bào)告

項(xiàng)目概述

該項(xiàng)目展示了如何模擬潛艇周圍的外部流體流動(dòng)的示例

艦船自航評(píng)估和研究通常是由拖曳水池自航試驗(yàn)實(shí)現(xiàn)，實(shí)施周期長(zhǎng)，耗資大。采用流體動(dòng)力數(shù)值仿真分析技術(shù)，能夠系統(tǒng)分析和研究各種水下航行器的航行性能，指導(dǎo)水下航行器設(shè)計(jì)，提出優(yōu)化設(shè)計(jì)方案和改進(jìn)航行性能的措施。

本項(xiàng)目對(duì)潛艇的水動(dòng)力航行性能進(jìn)行了分析和研究。

模型簡(jiǎn)化

本算例使用幾何來(lái)源simscale官網(wǎng)，幾何模型如圖1所示。

1. 潛艇幾何簡(jiǎn)化模型

網(wǎng)格設(shè)置

本算例采用snappyHexMesh對(duì)幾何模型進(jìn)行網(wǎng)格劃分（如圖2），詳細(xì)參數(shù)設(shè)置如下所示：

geometry

{solid_0

{type triSurfaceMesh;

file "solid_0.stl";

}

innerbox1

{type searchableBox;

min (-10 -15 -10);

max ( 80 15 15);

}

innerbox2

{type searchableBox;

min (-75 -15 -10);

max ( 90 15 15);

}

};

castellatedMeshControls

{maxLocalCells 2000000;

maxGlobalCells 4000000;

minRefinementCells 1;

maxLoadUnbalance 0.2;

nCellsBetweenLevels 4;

resolveFeatureAngle 30;

allowFreeStandingZoneFaces false;

features

(

{file "solid_0.extendedFeatureEdgeMesh";

level 4;

}

);

refinementSurfaces

{solid_0

{level (4 4);

patchInfo

{ type wall;

inGroups (solid_0Group);

}

}

}

refinementRegions

{solid_0

{mode distance;

levels ((1 4));

}

innerbox1

{mode inside;

levels ((1E15 2));

}

innerbox2

{mode inside;

levels ((1E15 1));

}

}

locationInMesh (-120 0 0);

}

snapControls

{nSmoothPatch 3;

tolerance 3.0;

nSolveIter 300;

nRelaxIter 5;

nFeatureSnapIter 10;

implicitFeatureSnap true;

explicitFeatureSnap false;

multiRegionFeatureSnap false;

}

addLayersControls

{relativeSizes true;

layers

{

"solid_0_.*"

{nSurfaceLayers 5;

}

}

expansionRatio 1.3;

finalLayerThickness 0.3;

minThickness 0.001;

nGrow 0;

featureAngle 180;

slipFeatureAngle 75;

nRelaxIter 5;

nSmoothSurfaceNormals 1;

nSmoothNormals 3;

nSmoothThickness 10;

maxFaceThicknessRatio 0.5;

maxThicknessToMedialRatio 0.3;

minMedianAxisAngle 90;

nBufferCellsNoExtrude 0;

nLayerIter 50;

nRelaxedIter 20;

}

meshQualityControls

{maxNonOrtho 65;

maxBoundarySkewness 20;

maxInternalSkewness 4;

maxConcave 80;

minVol 1e-13;

minTetQuality 1e-15;

minArea -1;

minTwist 0.01;

minDeterminant 0.001;

minFaceWeight 0.02;

minVolRatio 0.01;

minTriangleTwist -1;

nSmoothScale 4;

errorReduction 0.75;

relaxed

{maxNonOrtho 75;

}

}

writeFlags

(scalarLevels // write volScalarField with cellLevel for postprocessing

layerSets // write cellSets, faceSets of faces in layer

layerFields // write volScalarField for layer coverage

);

mergeTolerance 1E-6;

1. 潛艇網(wǎng)格劃分

2. 網(wǎng)格信息參數(shù)及網(wǎng)格質(zhì)量參數(shù)如下所示：

3. 網(wǎng)格信息參數(shù)

網(wǎng)格總數(shù)

---

數(shù)量 1544724 4346105 1402876 
網(wǎng)格類型 
類型 hexahedra prisms tet wedges polyhedra 數(shù)量 1280641 21250 25 100957 網(wǎng)格質(zhì)量 
評(píng)價(jià)指標(biāo) 最大縱橫比 最小體積 最大非正交性 最大歪斜率 值 19.795 6.38e-005 64.11 5.33

邊界條件參數(shù)

該算例湍流模型選用K-Omega SST模型。外流場(chǎng)壁面應(yīng)用對(duì)稱平面邊界條件，進(jìn)出口邊界條件見(jiàn)表1。

表1 邊界條件參數(shù)

邊界條件 參數(shù)

---

速度進(jìn)口 15m/s 壓力出口 0Pa

求解器參數(shù)設(shè)置

fvSchemes設(shè)置

ddtSchemes {

default steadyState;

}

gradSchemes {

default Gauss linear;

grad(U) Gauss linear;

grad(p) Gauss linear;

}

divSchemes {

default none;

div(phi,U) bounded Gauss upwind;

div(phi,omega) bounded Gauss upwind;

div((nuEff*dev2(T(grad(U))))) Gauss linear;

div(phi,k) bounded Gauss upwind;

}

laplacianSchemes {

default Gauss linear corrected;

laplacian(nuEff,U) Gauss linear corrected;

laplacian((1|A(U)),p) Gauss linear corrected;

laplacian(nu,U) Gauss linear corrected;

}

interpolationSchemes {

default linear;

interpolate(HbyA) linear;

}

snGradSchemes {

default corrected;

}

fluxRequired {

default no;

p ;

}

wallDist

{method meshWave;

}

fvSolution設(shè)置

solvers {

p {

relTol 0.005;

cacheAgglomeration on;

nPreSweeps 0;

agglomerator faceAreaPair;

nCellsInCoarsestLevel 10;

solver GAMG;

nPostSweeps 0;

mergeLevels 1;

smoother GaussSeidel;

tolerance 1e-06;

}

k {

relTol 0.01;

preconditioner DILU;

tolerance 1e-06;

solver PBiCG;

}

U {

relTol 0.01;

preconditioner DILU;

tolerance 1e-05;

solver PBiCG;

}

omega {

relTol 0.01;

preconditioner DILU;

tolerance 1e-06;

solver PBiCG;

}

}

relaxationFactors {

fields {

p 0.3;

}

equations {

omega 0.7;

k 0.7;

U 0.7;

}

}

SIMPLE {

pRefValue 0.0;

residualControl {

p 1e-06;

k 1e-06;

U 1e-06;

omega 1e-06;

}

nNonOrthogonalCorrectors 0;

pRefCell 0;

}

controlDict設(shè)置

application simpleFoam;

startFrom startTime;

stopAt endTime;

purgeWrite 0;

writeFormat ascii;

writePrecision 12;

writeCompression on;

timeFormat general;

timePrecision 12;

runTimeModifiable yes;

deltaT 1.0;

startTime 0.0;

writeInterval 1000;

adjustTimeStep no;

endTime 2000.0;

writeControl timeStep;

functions {

}

計(jì)算結(jié)果

本算例計(jì)算總步長(zhǎng)為1272步時(shí)云圖如下所示：