[Ali Fauze]

Hello Adrian,

Thank you for the response,

The geometry and material definition I modified the existing Aorta3D model and then I verified if the materials are correctly set in Paraview, And the same for the discretization and also I refined my model but I does remarked any significant change. Maybe if I can share with you a screenShot of the inlet, it will give you an idea.

Thanks for your help.
Best regards.

[Ali Fauze]

Hello Adrian,

Thanks for your response, sure!
Fluid properties:
Density: 997 Kg/m3
Kinematic Viscosity 8.927e-7 m2/s
Inlet Velocity 1 m/s
Dynamics used –> SmagorinskyBGK
Resolution –> 25
DeltaX –> 0.004
deltaT –> 0.0004
Descriptor D3Q19
Inlet –> smooth start-up 1m/s velocity in (checked the velocity inlet in paraview) and InterpolatedVelocityBoundqry is used
Outlet –> InterpolatedPressureBoundqry is used

I am at your disposal for any further information.

Thanks for your help.
Best regards.

[Ali Fauze]

Dear Dr. Mathias,

I appreciate your prompt response. After running the simulation with the Rayleigh-Bénard 3D example parameters, adjusting Ra and Pr values, I am pleased to report that the simulation did not diverge. However, the results obtained were unexpected. I observed the flow temperature and density both increased, contrary to the anticipated decrease in density. I attempted to fixe this issue by modifying the ThermalUnitConverter, and changing the physics model. Unfortunately, the simulation now diverges at the first time step.

Given that my ∆T is approximately 205°C, I am uncertain about the appropriate characteristics to assign to the ThermalUnitConverter at this temperature. Could you provide guidance on which temperature the characteristics shoud be assigned (Tmax or T0 …)?

Additionally, I would like to inquire if there is a recommended method for tracking convergence, like the transport equations used in RANS simulations.

Best regards,
Ali

[Ali Fauze]

Hello mathias,

Thank you for your response. Does an ‘opening’ boundary exist in OpenLB to allow the flow to enter or exit freely?

BR,
Ali

[Ali Fauze]

Dear community,

I resolved the problem using the functor IndicatorCircle3D.

BR.
Ali

[Ali Fauze]

Following is my PrepareGeometry function

void prepareGeometry(SuperGeometry<T,3>& superGeometry, ThermalUnitConverter<T, NSDESCRIPTOR, TDESCRIPTOR> &converter, IndicatorF3D <T> &indicator, STLreader <T> &stlReader)
{
OstreamManager clout (cout, “prepareGeometry”);
clout << “Prepare Geometrry ..” << endl;

superGeometry.rename (0, 1, indicator);
superGeometry.rename (1, 2, stlReader);

superGeometry.clean ();
Vector<T, 3> origini = superGeometry.getStatistics().getMinPhysR(1);
//origin[1] += converter.getConversionFactorLength() / 2.;
//origin[2] += converter.getConversionFactorLength() / 2.;

Vector<T, 3> extendi = superGeometry.getStatistics().getMaxPhysR(1);
//extend[1] = extend[1] – origin[1] – converter.getConversionFactorLength()/2.;
//extend[2] = extend[2] – origin[2] – converter.getConversionFactorLength()/2.;
//IndicatorCuboid3D<T> inlet({-0.1, -0.1, 0.0}, {0.1,0.1,0.0});
extendi[0] = superGeometry.getStatistics().getMaxPhysR(1)[0];
extendi[1] = superGeometry.getStatistics().getMaxPhysR(1)[1];
extendi[2] = superGeometry.getStatistics().getMinPhysR(1)[2];

//IndicatorCuboid3D<T> outlet({-0.1, -0.1, 10.0}, {0.1, 0.1, 10.0});
Vector<T, 3> origino = superGeometry.getStatistics().getMinPhysR(1);
origino[2] = superGeometry.getStatistics().getMaxPhysR(1)[2];
Vector<T, 3> extendo = superGeometry.getStatistics().getMaxPhysR(1);

//IndicatorCuboid3D<T> heated_face({-0.1, -0.1, 0.0}, {-0.10, 0.1, 10.0});
Vector<T, 3> originh = superGeometry.getStatistics().getMinPhysR(1);
Vector<T, 3> extendh = superGeometry.getStatistics().getMaxPhysR(1);
extendh[0] = superGeometry.getStatistics().getMinPhysR(1)[0];

clout << “inlet origin ” << origini << “inlet extend” << extendi
<< “outlet origin” << origino << “outlet extend” << extendo
<< “heated face origin” << originh << “heated face extend” << extendh
<< endl;
IndicatorCuboid3D<T> inlet(extendi, origini);
superGeometry.rename(2, 3, 1, inlet);
IndicatorCuboid3D<T> outlet(extendo, origino);
superGeometry.rename(2, 4, 1, outlet);
IndicatorCuboid3D<T> heated_face(extendh, originh);
superGeometry.rename(2, 5, 1, heated_face);

superGeometry.clean ();
superGeometry.innerClean ();
superGeometry.checkForErrors ();

superGeometry.print ();
clout << “Prepare Geometry … OK” << endl;
}
I would like also to put a part of my output but i’am blocked.

[Ali Fauze]

Hello Adrian,

I have the same problem, but I verified my STL file using blender, and also in my output, the MinPhysR is equal to my min node, and the same for the MaxPhysR, and y PhysDeltaX=0.00125 m. And I tried to define my vectors manually, and then getting the statistics from the simulation. Then I tried also both definition of the IndicatorCuboid3D (olb::IndicatorCuboid3D< S >::IndicatorCuboid3D ( Vector< S, 3 > extend,Vector< S, 3 > origin ) and this one
olb::IndicatorCuboid3D< S >::IndicatorCuboid3D ( S xlength, S ylength, S zlength, Vector< S, 3 > center )) and always I have the same error.
Do you have any suggestion to fixe the problem?

Best Regards
Ali

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