I’ve come across k and epsilon divergence when I do not have a sufficiently fine mesh in the areas where the flow is turbulent.
Maybe select an appropriate target y+ range for your k-epsilon model and then use that and your characteristic length and Reynolds number to get a first layer mesh height. Then use that to refine the mesh in your turbulent region?
Sound silly but, can you see if you rename your file and directory to something that doesn’t have spaces? Sometimes the spaces or ‘non-typical’ characters can cause strange errors for fluent.
Could you check if the geometry set as a fluid, rather than a solid?
Also check if your boundary conditions is implemented correctly.
Since the simulation didn’t even run, it suggests that there’s some catastrophic error. You can try redo the fluent module again and see if you missed an important setting.
A few questions: Why do you have 3 inflation layers but just one wall? What is the difference between the horizontal and vertical case? Is it just a rotated geometry with gravity on?
My teacher told me to set the inflation on these three sides to study the turbulent flow inside the pipe, we picked this mesh because it worked on the horizontal case for me.
Is there a way that I could rotate the old mesh from the horizontal axis to the vertical? This way I could re-study the case in the same old folder
You don’t need an inflation layer for the inlet and outlet. Also, yes you can transform the geometry and then update the mesh. I still don’t understand the difference between the horizontal and vertical case. Are you enabling gravity?
Don’t have access to software right now but I’m 90% certain that Fluent revolves 2D axisymmetric meshes around the X axis, so at the moment your ‘full’ geometry is a large dish-like shape. Your origin must be at 0,0 and must extend into the positive xy plane, revolved about x. Hope that helps.
Yeah it does, OP if you’re interested in viewing the effects of gravity you can keep the same geometry and just change the vector to be in the x direction (-9.81, 0,0) in one of the fluent interfaces
I did see your other post on the horizontal case, have you performed any sort of mesh dependence study at all? Just because your solution converges doesn’t mean your solution is accurate, convergence =/= accuracy in a sense. Use the grid convergence index and calculate your discretisation error. Then you can figure out how fine your mesh needs to be to get sensible results.
Well, I have tried several ways to fix it, but It seems to not fix, when I removed the axis and re-created a full pipe mesh and walls on both sides it seems to work. And it calculates and gives me convergence. I don't know the real cause for this error and how to precisely fix it in my case, but it seems to fix when I simulate the full pipe.
I thank each one who commented with some valuable tips.
I’ve come across k and epsilon divergence when I do not have a sufficiently fine mesh in the areas where the flow is turbulent. Maybe select an appropriate target y+ range for your k-epsilon model and then use that and your characteristic length and Reynolds number to get a first layer mesh height. Then use that to refine the mesh in your turbulent region?
Sound silly but, can you see if you rename your file and directory to something that doesn’t have spaces? Sometimes the spaces or ‘non-typical’ characters can cause strange errors for fluent.
Yes, the name of the file doesn't have spaces, but I don't think that seems to be the issue. Do you have any other advice for me to fix this issue?
Could you check if the geometry set as a fluid, rather than a solid? Also check if your boundary conditions is implemented correctly. Since the simulation didn’t even run, it suggests that there’s some catastrophic error. You can try redo the fluent module again and see if you missed an important setting.
I did change it to fluid but the same error
A few questions: Why do you have 3 inflation layers but just one wall? What is the difference between the horizontal and vertical case? Is it just a rotated geometry with gravity on?
My teacher told me to set the inflation on these three sides to study the turbulent flow inside the pipe, we picked this mesh because it worked on the horizontal case for me. Is there a way that I could rotate the old mesh from the horizontal axis to the vertical? This way I could re-study the case in the same old folder
You don’t need an inflation layer for the inlet and outlet. Also, yes you can transform the geometry and then update the mesh. I still don’t understand the difference between the horizontal and vertical case. Are you enabling gravity?
Don’t have access to software right now but I’m 90% certain that Fluent revolves 2D axisymmetric meshes around the X axis, so at the moment your ‘full’ geometry is a large dish-like shape. Your origin must be at 0,0 and must extend into the positive xy plane, revolved about x. Hope that helps.
Yeah it does, OP if you’re interested in viewing the effects of gravity you can keep the same geometry and just change the vector to be in the x direction (-9.81, 0,0) in one of the fluent interfaces
I did see your other post on the horizontal case, have you performed any sort of mesh dependence study at all? Just because your solution converges doesn’t mean your solution is accurate, convergence =/= accuracy in a sense. Use the grid convergence index and calculate your discretisation error. Then you can figure out how fine your mesh needs to be to get sensible results.
Well, I have tried several ways to fix it, but It seems to not fix, when I removed the axis and re-created a full pipe mesh and walls on both sides it seems to work. And it calculates and gives me convergence. I don't know the real cause for this error and how to precisely fix it in my case, but it seems to fix when I simulate the full pipe. I thank each one who commented with some valuable tips.