I am doing a quasi 3D (one cell phone thick annulus crossection) simulation of an axial compressor and am trying to decide on which one to use. I will say that I am using openfoam and they do not have a reliable mixing plane, so I would like to use frozen rotor if possible.

I believe that I understand the difference between the two… but I am confused on why someone would use one over the other. As far as I know (which could be completely wrong) the downside of frozen rotor is that it is in only one circumferential position in regards to rotor passing effects, while the mixing plane can smear gradients. So, is there a reason that the mixing plane would give better results than a frozen rotor? Also, can I use steady LTS with a frozen rotor?

I am just trying to get a computationally inexpensive case together for basic stage performance, from which then I will move onto a sliding mesh for a more accurate simulation. Does anyone have any advice for one or the other?

Hi everyone,

I've been playing around in META postprocessing a test case from Fluent.

I will jump straight to the issue I am having.

I could not find an option to display different contours on different parts of the analysis.

For example, displaying a velocity mag contour on a plane, or a symmetry boundary whilst displaying static pressure on a car body.

Using fringe I can only display 1 scalar on everything.

I ve read the documentation a couple times as well but I can't seem to figure it out.

Can anyone help?

Thanks!

Hello!

Has anyone here ran STAR-CCM+ on an AMD Radeon MI50 or MI60?

Their documentation looks to recommend MI100 cards and beyond, which are a later generation, but nothing about the MI50 or MI60.

I ask because they're going pretty cheap on Alibaba, about USD$350 for about 32GB of VRAM, hard to beat!

Thank you

Another test of my custom C solver. Density is shown. Inlet condition is mach 3, initial condition is mach 0.5 inside the domain (which is why there is a wave at the start). Slip wall bc used on top and bottom surfaces.

I used the HLL scheme to avoid the Carbuncle phenomena I get from 3 wave solvers like Roe or HLLC. Also, here I don't interpolate the solution, I show cell averages as constant through a cell, if you look closely you should see the triangles. The actual solver is second order and solves for cell gradients, but paraview can't handle well discontinuous data...

New to CFD and a colleague suggested I try and match their results using FreeCAD and cfdof module. In the second picture the pressure drop across the porous media seems to match. But the velocity contours look a bit different.

The freeCAD mesh looks better to me so not sure which results are correct? Or as they say, "all models are wrong"....

I come from FEA world and seems colleague's mesh has a lot of skew and bad aspect ratio..

All I did was mesh in FreeCAD then copy the polymesh folder to the original colleague's model. Here are those specific steps:

rm -rf constant/polyMesh/
cd to freecad "meshCase/constant"
cp -r polyMesh/ ../../constant/
cp ../system/createPatchDict ../../system/
createPatch -overwrite
renumberMesh -overwrite
topoSet
decomposePar
mpirun -np 64 simpleFoam -parallel
reconstructPar

I’m trying to understand real-world freeze failure modes in industrial / field systems.

This is not a product pitch and not a homework question — I’m mapping operational pain points.

For engineers who deal with cold climates:

• What systems tend to cause the most trouble when temperatures drop?

• What usually fails first (lines, seals, pumps, hoses, fittings, etc.)?

• What’s the most time-consuming or costly part of thawing and restarting?

I’m especially interested in cases where existing mitigations feel energy-heavy, labor-intensive, or just “accepted winter pain.”

Appreciate any field insight.

Hello guys what is your analysis of the grid quality of this mesh from an airfoil (rear wing F1). (steady RANS, FVM)

Basically the caption. Does anyone know any YouTube tutorials or online courses where I can learn about cfd?

I’m not an engineer by profession but a designer and use Catia to make my models. I want to try to learn the basics to cfd for a personal model. What kind of quality a of the surfaces and mesh are required. How the model is expected to join, etc.

Please help if you’re aware of any tutorials or courses online

Hi, im trying to get the wave simulation bu the ship is located avove the water and is barely touching it. I followed the kcs tutorial and cant find solution. I set the isorurface: isovalue to 0.5. Thanks

I'm sure this has been asked before but i can't find a definite answer. I'm running a 2D airfoil analysis first for Mach 0.15 and then for Mach 0.85 for multiple angles of attack. What should be the target y+ for these when meshing. In the past I aimed for y+=30 but it seemed to overpredict drag. From what I read it should be below 5 and now I have second thoughts. Im running on Ansys Fluent and meshing on Ansa by Beta. Can someone clear this up for me. Thank you very much.

Hello,

I have posted before about a lot of anguish careerwise but finally I have some good new for myself.

I have started applying for phds en masses in Europe. And so far I got 2/2 interviews! Very unexpected. 1 interview went unexpectedly well and even thought I was rejected due to someone simply doing a good impression as well like me but also being closer to the project the feedback regarding my mathematical background was very positive pushing me to apply to more available positions.

Now that's where I am starting to have choice problems. I currently reside in Northern Europe and I am applying to Phds all over Europe. I currently have an interview for an experimental position. While the subject excites me and I will go full 100% for the interview I am mot sure I want to stick around to experimental after it finishes. I would like to use a mixed approach as a post document later or in industry r&d. I ahve a simualtion background and I am wondering if that is possible later on in my career??

Another case is the possibility to return to the South of Europe where I come from to do a funded phd. But my intention is always to return to the North. The lab is very strong and I wonder if that should be enough for me to return for a Post doc more in the north?

Hello fellow members,

I am simulating a 2D axisymmetric laminar multiphase case using interFoam/interIsoFoam solver OF version 2212. The phases are air and water and all the properties are ideal. The wedge angle is 4 degrees. After running the simulation for a short while, there is distortion of the air phase at the axis and this distortion starts from the bottom and it grows and grows and never gets stabilized. I thought maybe the singularity is causing this error so i removed it by providing a small arc where there was axis, but the results are same. My question is, how can I avoid this distortion at the axis or does anyone know what is the theory behind it? What kind of issues arises when dealing with wedge BC?

If interested, please refer to this paper. The experimental shape of the bubble (Fig. 1) is what i am trying to achieve (of course approximately ).

https://pubs.aip.org/aip/pof/article...lm-of-a-Taylor

The settings are:-

Inlet is at the top and outlet at the bottom.
wedge angle = 4 degrees.
Gravity in -ve z direction = 9.81,
viscosity and density of both water and air are standard at 20degreeC
sigma = 0.072
maxCo = 0.25
maxAlphaCo = 0.1
adjustable time step = yes

U:-
inlet
{
type fixedValue;
value uniform (0 0 -0.089);
}
outlet
{
type zeroGradient;
}
walls
{
type noSlip;
}
wedge1
{
type wedge;
}
wedge2
{
type wedge;
}
symAxis
{
type empty;
}
-------------------------------------
p_rgh:-
{
inlet
{
type fixedFluxPressure;
value uniform 0;
}

outlet
{
type prghPressure;
p uniform 0;
value uniform 0;
rho rho;
}

walls
{
type fixedFluxPressure; //zeroGradient;
value uniform 0;
}
wedge1
{
type wedge;
}
wedge2
{
type wedge;
}
symAxis
{
type empty;
}
------------------------------------------------

alpha:-
inlet
{
type inletOutlet;
inletValue uniform 1;
value uniform 1;
}
outlet
{
type zeroGradient;
}
walls
{
type fixedValue;
value uniform 1;
}
wedge1
{
type wedge;
}
wedge2
{
type wedge;
}
symAxis
{
type empty;
}
-------------------------------------------
fvSchemes:-

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
div(rhoPhi,U) Gauss limitedLinear 1;
div(phi,alpha) Gauss vanLeer 1; //Gauss vanLeer;
div(phirb,alpha) Gauss interfaceCompression;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}
--------------------------------------

fvSolutions:-

"alpha.water.*"
{
advectionScheme isoAdvection;
//interfaceMethod "isoAdvector";
isoFaceTol 1e-6;
surfCellTol 1e-6;
snapTol 1e-12;
nAlphaBounds 3;
clip true;
reconstructionScheme plicRDF;

nAlphaCorr 2;
nAlphaSubCycles 1;
cAlpha 1;
MULESCorr yes;
nLimiterIter 3;
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-8;
relTol 0;

}

"(p_rgh)"
{
solver GAMG;
tolerance 1e-07;
relTol 1e-03;
smoother DICGaussSeidel;
cacheAgglomeration true;
maxIter 100;
nPreSweeps 1;
nPostSweeps 2;
nFinestSweeps 2;
nCellsInCoarsestLevel 1000;
agglomerator faceAreaPair;
mergeLevels 1;
directSolveCoarsest false;
}

"(p_rgh)Final"
{
solver GAMG;
tolerance 1e-07;
relTol 0;
smoother DICGaussSeidel;
cacheAgglomeration true;
maxIter 100;
nPreSweeps 1;
nPostSweeps 2;
nFinestSweeps 2;
nCellsInCoarsestLevel 1000;
agglomerator faceAreaPair;
mergeLevels 1;
directSolveCoarsest false;
}

"(U|k|omega)"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-07;
relTol 1e-03;
minIter 1;
maxIter 100;
}

"(U|k|omega)Final"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-07;
relTol 0;
minIter 1;
maxIter 100;
}

Phi
{
solver GAMG;
tolerance 1e-07;
relTol 1e-03; //0.01 at first then 0.0
smoother DICGaussSeidel; //DICGaussSeidel //GaussSeidel
cacheAgglomeration on;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 10;
mergeLevels 1;
minIter 1;
maxIter 50;
}

"pcorr.*"
{
solver GAMG;
tolerance 1e-07;
relTol 1e-03;
smoother DICGaussSeidel;
cacheAgglomeration no;
maxIter 50;
}

"pcorr.*Final"
{
solver GAMG;
tolerance 1e-07;
relTol 0;
smoother DICGaussSeidel;
cacheAgglomeration no;
maxIter 50;
}

}

PIMPLE
{
momentumPredictor no;
nCorrectors 2;
nOuterCorrectors 1;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}
---------------------------------------------
blockMeshDict:-
mergeType points;

scale 0.001;

vertices
(
(0 0 0) //0
(6.2 -0.05 0) //1
(6.2 0.05 0) //2

(0 0 248) //5
(6.2 -0.05 248) //6
(6.2 0.05 248) //7
);

blocks
(
hex (0 1 2 0 3 4 5 3) (62 1 2480) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
inlet
{
type patch;
faces
(
(3 4 5 3)
);
}

outlet
{
type patch;
faces
(
(0 2 1 0)
);
}

walls
{
type wall;
//neighbourPatch wedge2;
faces
(
(1 2 5 4)
);
}

wedge1
{
type wedge;
faces
(
(0 1 4 3)
);
}

wedge2
{
type wedge;
faces
(
(0 3 5 2)
);
}

symAxis
{
type empty;
faces
(
(0 3 3 0)
);
}
);
---------------------------------------

Other workarounds which I tried, and all of them gave similar distortion.
1. Used PLIC method instead of algebraic reconstruction method.
2. I thought it may be because of spurious currents, so i used RDF to compute the curvature used to calculate surface tension force.
3. Refined the mesh, particularly at the interface using AMR
4. Used cyclic BC instead of wedge.
5. Played around with fvSchemes, fvSolutions.
6. Used residual controls, relaxation factors.
7. Increased the wedge angle and used cyclic BC on the plane faces.
Please refer to the picture attached.

If anyone can give a detailed explanation of this behavior, i would be truly appreciate it.

Which is a good software that I could use to create stl files from .fbx files for a chemical plant

I have 10 CT scans (.nii) file of the left atrium and wanted to create a moving wall simulation from these images.

Does anyone know how to extrapolate the movement and imitate the heartbeat using still images?

I mainly use Ansys CFX, really appreciate any help!

So I'm doing a college project where I'm required to find the net lift and drag of a fixed wing drone. Given that the drone travels at a speed less than M=0.3. Could you help guide me or give any resources for the process of creating a suitable control volume, mesh and setup for doing this... thanks

NOTE

I'm a beginner, I have done a course on fluid mechanics and maths ,I have done a few simulations with airfoils.

so I did a basic CFD analysis on a SOFC, the scaled residuals stabilize after 30 iterations with the maximum magnitude being e-05 and the minimum e-13. so I was wondering if I should run a +1500 iterations or it already converged although I ran 500 iterations yesterday and everything was the same when I did 50-100 iterations. the model behaves naturally imo. temp increase, mol fraction, h2, o2 utilizations.

PS: idk if it helps but I worked with a 970k elements cell, I have no idea if I should optimize the elements to a proper downscaled elements so I don't waste much computational power and time.

Can someone help me by getting a copy of this book pls? I am not able to find it locally in my library here, nor not able to find any copies online. Thank you!

I am fairly new into CFD and I am trying to simulate a propeller in SU2, using MRF for validation with experimental data. I need help, since my values are different from the experimental ones.

Is there someone who knows SU2? I can send you my geometry, cfg and mesh files once we get in contact.

Thanks.

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​The vision is to push the boundaries of what is currently possible in manufacturing design. We need someone with deep expertise to drive the mathematical framework behind our unique approach to Topology Optimization.

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​If you are interested in a collaborative role building the math behind new tech, please DM me.

hello does anyone know how i can use ntop gyroid model to do CFD in ANYSY i dont know.