[sega]

Hi.

Just installed OpenFOAM 1.7 on my Ubuntu 10.04 LTS.
Works well - easiest installation so far !

I'm just running the new floating object tutorial case.
Can anybody tell me how the case is structured?

It looks really interesting and I would like to know more about it.
Especially about the field pointDisplacement and the boundary condition sixDoFRigidBodyDisplacement.

Happy brainstorming.
sega

[anmartin]

Hello,

Sorry, but have you running the tutorial example without any problem (Floating point exception).

I would like to run the example, but I obtain an error.

Best regards

[sega]

Originally Posted by anmartin

Hello,

Sorry, but have you running the tutorial example without any problem (Floating point exception).

I would like to run the example, but I obtain an error.

Best regards

Everything is fine here.

[anmartin]

Sorry to trouble you,

I have installed this version of linux,
Distributor ID: Ubuntu
Description: Ubuntu 10.04 LTS
Release: 10.04
Codename: lucid

I have installed OF170 as is described in webpage (Ubuntu/Debian pack installation), I try to run the floatingObject tutorial example copy it from multiphase to my run directory and I obtain the following error.
Time = 1.2731

Centre of mass: (0.373595449653 0.351882909424 0.482406400186)
Linear velocity: (-0.357961120598 -0.419740647472 -0.322074163028)
Angular velocity: (1.07106504184 -0.903173170713 -0.0110838047329)
GAMG: Solving for cellDisplacementx, Initial residual = 0.0056044966347, Final residual = 5.8395571122e-06, No Iterations 5
GAMG: Solving for cellDisplacementy, Initial residual = 0.00549399203972, Final residual = 5.71456061284e-06, No Iterations 5
GAMG: Solving for cellDisplacementz, Initial residual = 0.00997063228984, Final residual = 3.85256246304e-06, No Iterations 6
Execution time for mesh.update() = 0.68 s
time step continuity errors : sum local = 3.84344042594e-10, global = 2.49126712936e-11, cumulative = -0.000105905828067
GAMGPCG: Solving for pcorr, Initial residual = 1, Final residual = 2.81917055336e-06, No Iterations 7
time step continuity errors : sum local = 1.08353248665e-15, global = 2.55464254723e-16, cumulative = -0.000105905828067
MULES: Solving for alpha1
Liquid phase volume fraction = 0.533377598497 Min(alpha1) = -3.16898215629e+294 Max(alpha1) = 2.40723995432
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam170/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam170/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 in "/lib/libc.so.6"
#3 Foam::fv::gaussGrad<double>::grad(Foam::GeometricF ield<double, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam170/applications/bin/linux64GccDPOpt/interDyMFoam"
#4 Foam::fv::gaussGrad<double>::grad(Foam::GeometricF ield<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libfiniteVolume.so"
#5 Foam::tmp<Foam::GeometricField<Foam:uterProduct< Foam::Vector<double>, double>::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::grad<double>(Foam::GeometricField<doubl e, Foam::fvPatchField, Foam::volMesh> const&, Foam::word const&) in "/opt/openfoam170/lib/linux64GccDPOpt/libinterfaceProperties.so"
#6 Foam::tmp<Foam::GeometricField<Foam:uterProduct< Foam::Vector<double>, double>::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::grad<double>(Foam::GeometricField<doubl e, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam170/lib/linux64GccDPOpt/libinterfaceProperties.so"
#7 Foam::LimitedScheme<double, Foam::vanLeerLimiter<Foam::NVDTVD>, Foam::limitFuncs::magSqr>::limiter(Foam::Geometric Field<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libfiniteVolume.so"
#8 Foam::limitedSurfaceInterpolationScheme<double>::w eights(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libinterfaceProperties.so"
#9 Foam::surfaceInterpolationScheme<double>::interpol ate(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libinterfaceProperties.so"
#10 Foam::fv::gaussConvectionScheme<double>::interpola te(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libfiniteVolume.so"
#11 Foam::fv::gaussConvectionScheme<double>::flux(Foam ::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam170/lib/linux64GccDPOpt/libfiniteVolume.so"
#12
in "/opt/openfoam170/applications/bin/linux64GccDPOpt/interDyMFoam"
#13
in "/opt/openfoam170/applications/bin/linux64GccDPOpt/interDyMFoam"
#14
in "/opt/openfoam170/applications/bin/linux64GccDPOpt/interDyMFoam"
#15 __libc_start_main in "/lib/libc.so.6"
#16
in "/opt/openfoam170/applications/bin/linux64GccDPOpt/interDyMFoam"
Floating point exception

If you could help me I will be very grateful

Best regards,

[sega]

And you have a 64bit machine and operating system?

[anmartin]

I have the following system and cpu

Ubuntu version 10.04 64 bits
anmartin@anmartin2:~/OpenFOAM/OpenFOAM-1.7.0/bin$ uname -ar
Linux anmartin2 2.6.32-22-generic #36-Ubuntu SMP Thu Jun 3 19:31:57 UTC 2010 x86_64 GNU/Linux

machine 64 bits too
anmartin@anmartin2:~/OpenFOAM/OpenFOAM-1.7.0/bin$ sudo lshw -C cpu
*-cpu
description: CPU
product: Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz
serial: To Be Filled By O.E.M.
slot: CPU 1
size: 1200MHz
capacity: 1200MHz
width: 64 bits
clock: 133MHz
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp x86-64 constant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm ida tpr_shadow vnmi flexpriority ept vpid cpufreq

Thank you for your help

Best regards

[yannH]

hi Anmartin,

Have you succeed with the floating point error? I have the same trouble but for me it works two times before this problem..

best regards,

yann

[anmartin]

Hi Yann,

Yes, Henry Weller solved my problem, (it is an issue with the initialization (or lack of it) of the pressure (p_rgh) which imparts an unphysical impulse on the object which then moves further than the mesh-motion can cope with).
You only need to pull the latest OpenFOAM-1.7.x recompile it and try it out, it works for me.
http://www.cfd-online.com/Forums/ope...-than-1-a.html
best regards,

[SD@TUB]

Hello FOAMers,

Before posting a new thread regarding the floatingObject tutorial i am continuing within this discussion.
I want to simualte free floating geometries in 2D and i am insecure how to proceed with setting appropriate boundary conditions especially for the pointDisplacement dictionary due to the dimensions expected from this input file. The values reffering to 3D, e.g. mass, moment of inertia, etc.
Is it possible to simulate 2D cases with the mesh motion solver provided in version 1.7.x, e.g. 2D wave tank (structures floating in long crested waves)?
Maybe someone could give me advice to perform such simulations!

Thanks in advance!
/Stefan

[Rose2011]

Hi Stefan (or anyone else),

Did you manage to simulate a 2D case of a floating object? I would like to do the same but am also having some difficulty in determining the correct parameters for the pointDisplacement file.

Thanks,
Rose

[Rose2011]

No one?


My problem is this: I have a floating box that should respond freely to waves generated at the inlet. I need three degrees of freedom, up/down, left/right and tilt side to side. My case is 2D in the xz plane. To me the obvious choice of the available constraints would be fixedPlane with a normal of (0 1 0). However this case only runs for 1 or 2 time steps and crashes with the following error:
--> FOAM FATAL ERROR:

Maximum number of sixDoFRigidBodyMotion constraint iterations (500) exceeded.

From function Foam::sixDoFRigidBodyMotion::applyConstraints(scal ar deltaT)
in file pointPatchFields/derived/sixDoFRigidBodyMotion/sixDoFRigidBodyMotion.C at line 134.

FOAM exiting

The simulation does run for a few seconds using fixedPlane with normal (0 0 1) but does not allow the box to rise or sink. The simulation crashes when my box twists the mesh.

Am I using the wrong combination of constraints? I am hoping that someone who has modelled a 2D floating object with 3DoF can give me some tips.

Thanks,
Rose

[CKH]

Have you tried fixedAxis?

For example, rolling (y-axis rotation) only:

constraints
        {
            maxIterations   500;

            fixedAxis1
            {
                sixDoFRigidBodyMotionConstraint fixedAxis;
                tolerance       1e-04;
                relaxationFactor 0.7;
                fixedAxisCoeffs
                {
                    axis            ( 0 1 0 );
                }
            }
        }