topic Re: Diverging problem for restrictor analysis in CFD Forum

Diverging problem for restrictor analysis

Anonymous — Fri, 24 Mar 2017 20:25:01 GMT

Hello Sir,

During Analysis of restrictor I have used 6 designs for simulation, but for the same boundary conditions and meshing, problems are

4 of them converged and produced good results but 2 of them are not converging even after trying many times. I am attaching the one file which diverges after 100 iterations?
And those 4 are also has not produced in one time.

please help me!

Re: Diverging problem for restrictor analysis

Jon.Wilde — Sat, 25 Mar 2017 06:02:30 GMT

Please attach a CFZ file 🙂

What are you changing in the geometry with each scenario?

Re: Diverging problem for restrictor analysis

Anonymous — Sat, 25 Mar 2017 10:51:44 GMT

hello sir,

Boundary conditions are :

inlet total pressure: 101325 pa
outlet Mass flow rate: 0.0703 kg/s

Sir, I am changing converging and diverging angle of restrictor in each scenerio.

regards,

Akshay Kumar

Re: Diverging problem for restrictor analysis

Anonymous — Sat, 25 Mar 2017 13:21:09 GMT

Hello sir,

Now I have done with different geometry but same thing is happening the flow starts flowing in reverse direction. I have also tried by changing advection scheme 4 which is for duct analysis, but results are same.

Please look in this matter. why it is happening so?

Re: Diverging problem for restrictor analysis

Anonymous — Sat, 25 Mar 2017 18:19:50 GMT

Hello sir,

Now very strange thing is happening.

first time with the same geometry same conditions i got the result which was converged.
but 2nd time same geometry same conditions, i am getting different results and diverged too.

please help me, I am not able to get why this is happening?

regards,

Akshay kumar

Re: Diverging problem for restrictor analysis

Jon.Wilde — Mon, 27 Mar 2017 06:58:23 GMT

A few points from me:

You need a far longer inlet and outlet
It is better to push flow in than pull it out - check out the compressible flow page here
From the guide above, you will see that you model might be under constrained
You need far more mesh to keep this stable, I would guess that so far, you have not seen a good converged solution#
Why not run 2D axisymmetric? FAR faster 🙂

Thanks for sharing

Jon

Re: Diverging problem for restrictor analysis

Anonymous — Mon, 27 Mar 2017 07:12:42 GMT

thank you so much sir for your valuable suggestions.

regards,

Akshay Kumar

Re: Diverging problem for restrictor analysis

Jon.Wilde — Mon, 27 Mar 2017 09:10:00 GMT

No problem.

Please mark my post as solution if you decide that it was indeed a solution for you 🙂