以DTCHullWave算例为例 ，使用dynamicmeshDict计算船舶波浪增阻，这里参数的意义是我所标注的这个意思吗？

[一朵苍凉]

个人理解：这里的centerofmass设置为（0 0 0 ）应该是固船坐标系的意思，在势流理论里面，可以通过取固定在物体重心处的坐标系来将物体匀速运动的问题转化成固定流速物体的绕流问题，大大简化计算。所以如果船舶只有航速贸易放开自由度，取这个坐标系是可以将船舶匀速运动的问题转化成船舶绕流问题的，这样就可以把非定常问题简化成定常问题了。

[souliam]

@一朵苍凉 不知道您能不能帮我看下我的算例，看看那儿可以优化以下？我的算例是重叠网格进行自由运动计算。运算几步以后就崩了，运动不对，但不知道那儿存在问题，可以的话，我上传详细的细节给您。

[一朵苍凉]

@souliam
运行很快崩溃的话，可能是存在非常致命的问题。首先确保网格是mesh ok的，然后确保物体的几何属性例如质量惯性矩这些都没问题，如果还是很快crash的话，可以适当增大pimple求解的外循环次数。

[souliam]

@一朵苍凉 这个算例我在商软starccm+里面已经算过，目前在openfoamv2012进行同样的计算。网格仿造DTChull算例，利用snappyHexMesh生成，我的求解文件输出是这样的，运动输出的6Dof结果感觉比较大，所以我认为可能是我的dynamicsMeshdict文件可能有问题，但不知道那儿有问题，您方便的话，再帮我看以下，指点一二，感谢。
Create time

Create mesh for time = 0

Selecting dynamicFvMesh dynamicOversetFvMesh
Selecting motion solver: sixDoFRigidBodyMotion
Applying solid body motion to entire mesh
Selecting sixDoFSolver Newmark
Translational constraint tensor (0 0 0 0 0 0 0 0 1)
Rotational constraint tensor (1 0 0 0 1 0 0 0 1)

PIMPLE: no residual control data found. Calculations will employ 2 corrector loops

Using LTS
Reading field p_rgh

Reading field U

Reading/calculating face flux field phi

Creating cellMask field to block out hole cells

Creating interpolatedCells field

Reading transportProperties

Selecting incompressible transport model Newtonian
Selecting incompressible transport model Newtonian
Selecting turbulence model type RAS
Selecting RAS turbulence model kEpsilon
RAS
{
RASModel kEpsilon;
turbulence on;
printCoeffs on;
Cmu 0.09;
C1 1.44;
C2 1.92;
C3 0;
sigmak 1;
sigmaEps 1.3;
}

Reading g

Reading hRef
Calculating field g.h

No MRF models present

No finite volume options present
DICPCG: Solving for pcorr, Initial residual = 1, Final residual = 9.39433050916e-07, No Iterations 467
Reading/calculating face velocity Uf

Starting time loop

Flow time scale min/max = 8.6866267787e-07, 0.0291922459613
Smoothed flow time scale min/max = 8.6866267787e-07, 0.0291922459613
Time = 0.001

PIMPLE: iteration 1
forces forces:
rho: rho
Not including porosity effects

Restraint translationDamper: force (-0 -0 -0)
Restraint rotationDamper: moment (-0 -0 -0)
6-DoF rigid body motion
Centre of rotation: (0 0 -0.461009082997)
Centre of mass: (0 0 -0.461009082997)
Orientation: (0.999999999122 -4.18404783667e-05 2.19816547713e-06 4.18405388615e-05 0.999999998746 -2.75277355352e-05 -2.19701370075e-06 2.75278274834e-05 0.999999999619)
Linear velocity: (0 0 0.0218340063689)
Angular velocity: (0.0550532334843 0.00439510067628 0.0836815815307)
cellVolumeWeight : detected 2 mesh regions

zone:0 nCells:1428000
zone:1 nCells:1108410

Marking patch-cells on zone 0
Marking patch-cells on zone 1

After patch analysis : nCells : 2536410
other : 2371976
patch : 141190
overset: 23244

Creating mesh-to-mesh addressing for region0 and region0 regions using cellVolumeWeight
meshToMesh: Using AABBTree method
Overlap volume: 2.68136988135
cellVolumeWeight : detected 3 mesh regions after overset

Front : fraction:1 size:23970
Overset analysis : nCells : 2536410
calculated : 2512836
interpolated : 23432
hole : 142

Execution time for mesh.update() = 56.91 s
smoothSolver: Solving for alpha.water, Initial residual = 1.32501360637e-07, Final residual = 5.40621940608e-09, No Iterations 1
Phase-1 volume fraction = 0.80497110631 Min(alpha.water) = 0 Max(alpha.water) = 1.00094392533
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.804971106201 Min(alpha.water) = -5.22912457509e-16 Max(alpha.water) = 1.00094392533
smoothSolver: Solving for alpha.water, Initial residual = 1.32287726888e-07, Final residual = 5.33117835751e-09, No Iterations 1
Phase-1 volume fraction = 0.80497110685 Min(alpha.water) = -3.28734455684e-21 Max(alpha.water) = 1.00148843719
Applying the previous iteration compression flux
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.804971106742 Min(alpha.water) = -3.32478347046e-14 Max(alpha.water) = 1.00148843719
DILUPBiCGStab: Solving for p_rgh, Initial residual = 1, Final residual = 0.00904252579238, No Iterations 4
time step continuity errors : sum local = 4.98432915358e-06, global = -4.35030739554e-09, cumulative = -4.35030739554e-09
DILUPBiCGStab: Solving for p_rgh, Initial residual = 0.000104613428998, Final residual = 9.48129717208e-07, No Iterations 95
time step continuity errors : sum local = 5.17819342099e-08, global = 9.75203425207e-09, cumulative = 5.40172685653e-09
smoothSolver: Solving for epsilon, Initial residual = 0.00318321052028, Final residual = 5.00754349231e-05, No Iterations 2
bounding epsilon, min: -0.00891808144257 max: 106.248958364 average: 1.03357845974
smoothSolver: Solving for k, Initial residual = 0.999999999979, Final residual = 0.0989395295117, No Iterations 1
PIMPLE: iteration 2
smoothSolver: Solving for alpha.water, Initial residual = 1.5141031309e-05, Final residual = 5.25145730347e-09, No Iterations 2
Phase-1 volume fraction = 0.804973015496 Min(alpha.water) = -7.90828268587e-26 Max(alpha.water) = 1.00074698501
Applying the previous iteration compression flux
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.804972981578 Min(alpha.water) = -0.000375075266952 Max(alpha.water) = 1.00074698501
smoothSolver: Solving for alpha.water, Initial residual = 1.54146759159e-05, Final residual = 5.35120277128e-09, No Iterations 2
Phase-1 volume fraction = 0.804974867545 Min(alpha.water) = -4.8534415386e-10 Max(alpha.water) = 1.0014871078
Applying the previous iteration compression flux
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.80497478029 Min(alpha.water) = -0.000141219315799 Max(alpha.water) = 1.0014871078
DILUPBiCGStab: Solving for p_rgh, Initial residual = 3.91238817862e-05, Final residual = 9.99981139229e-07, No Iterations 15
time step continuity errors : sum local = 1.97312896592e-06, global = 8.73490744761e-07, cumulative = 8.78892471617e-07
DILUPBiCGStab: Solving for p_rgh, Initial residual = 6.95825944208e-06, Final residual = 8.05766273076e-07, No Iterations 19
time step continuity errors : sum local = 1.37353052288e-06, global = -1.53311028217e-07, cumulative = 7.25581443401e-07
smoothSolver: Solving for epsilon, Initial residual = 0.0476145055724, Final residual = 0.00249278364183, No Iterations 6
bounding epsilon, min: -1.06527371456 max: 3100.56090246 average: 2.84781772564
smoothSolver: Solving for k, Initial residual = 0.79259262557, Final residual = 0.0311989522415, No Iterations 4
ExecutionTime = 112.02 s ClockTime = 112 s

Flow time scale min/max = 1.85015907037e-06, 1e+15
Smoothed flow time scale min/max = 1.85015907037e-06, 0.0296574788498
Time = 0.002

PIMPLE: iteration 1
forces forces:
rho: rho
Not including porosity effects

Restraint translationDamper: force (-0 -0 -187.685118747)
Restraint rotationDamper: moment (-637.846763149 -50.9216364354 -969.534803614)
6-DoF rigid body motion
Centre of rotation: (0 0 -0.459430003293)
Centre of mass: (0 0 -0.459430003293)
Orientation: (0.998240479028 -0.0584060732538 0.0102311601265 0.058508037056 0.998237177305 -0.00996731887657 -0.00963097244877 0.0105483862658 0.999897982755)
Linear velocity: (0 0 3.13632540091)
Angular velocity: (6.05745573944 18.6026037453 117.298982883)
cellVolumeWeight : detected 2 mesh regions

zone:0 nCells:1428000
zone:1 nCells:1108410

Marking patch-cells on zone 0
Marking patch-cells on zone 1

After patch analysis : nCells : 2536410
other : 2371976
patch : 141190
overset: 23244

Creating mesh-to-mesh addressing for region0 and region0 regions using cellVolumeWeight
meshToMesh: Using AABBTree method
Overlap volume: 2.67649933669
cellVolumeWeight : detected 4 mesh regions after overset

Front : fraction:1 size:24277
Overset analysis : nCells : 2536410
calculated : 2512742
interpolated : 23425
hole : 243

Execution time for mesh.update() = 54.91 s
[3] #0 Foam::error::printStack(Foam::Ostream&) at ??:?
[3] #1 Foam::sigFpe::sigHandler(int) at ??:?
[3] #2 ? in /lib/x86_64-linux-gnu/libpthread.so.0
[3] #3 Foam::symGaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> 一堆错误提示省略

Primary job terminated normally, but 1 process returned
a non-zero exit code. Per user-direction, the job has been aborted.

---

mpirun noticed that process rank 3 with PID 0 on node dell-optiplex-7070 exited on signal 8 (Floating point exception).

[souliam]

@一朵苍凉 dynamicMeshDict 这时我的6自由度文件

[一朵苍凉]

@souliam 看起来你释放了一个平动和三个转动，不确定你的惯性矩等几何参数设置是否正确。为什么浮体网格表面看起来那么稀？

[souliam]

@一朵苍凉 惯性矩这个我再确认一下，谢谢！上图显示的不是浮体表面网格，是背景网格和重叠区域网格的叠加一起。 目前的centerofmass以及orientation，在我的理解中似乎是一样的物理意义，质心？

[一朵苍凉]

@souliam 这个centerofmass是质心，orientation应该是旋转中心吧，一般可以默认旋转中心在质心处（个人理解）。

[souliam]

@一朵苍凉 好的，我认同你的解释，

[souliam]

@一朵苍凉 非常谢谢你！

[zqliu012345]

@zqliu012345
在DTCHullMoveing的算例中使用的是运动求解器你是rigidBodyMotion求解器，对于这个求解器的参数而言
其中是centreOfMass 这个参数表示的是重心在旋转重心的相对位置，而不是表面意思理解的中心的全局坐标，他要跟transform配合使用的一般transform的第一个括号表示坐标系不旋转（因为前面就是一个单位矩阵）后面括号的坐标是旋转中心，如下图所示（interFoam中的floatingObject算例）（0.5 .45 0.1）是这个附体的旋转中心，而他的重心的全局坐标不是上面的centreOfMass 是 这个变量表示重心和旋转重心在三个方向的距离，因为需要进行加减才能得到重心，这里他的重心（质心）就是（0.5+0,0.45+0, 0.1+0.25）即（0.5 0.45 0.35）

对于把重心当做旋转中心的情况 centreOfMass 里面就是全都是0 transform第一个括号都不变，第二个括号里面是重心的全局坐标（DTCHull算例就是这种情况 因此 他的centreofMass是（0 0 0））

[Sichan]

您好，我想在您这个回答的基础上再问一个问题。由于在rigidBodyMotion求解器中，centraOfMass是相对于centraOfRotation，那么sixDoFRigidBodyMotion求解器中的momentOfInertia改成rigidBodyMotion求解器中的interia应该做何种变换呢？