Vortex generators using fluent

Hardeep · July 21, 2013, 10:52

Hi guys,

Im fairly new to CFD. I've been trying to model a triangular vortex generator (VG) placed on a baseboard in the middle of a flow to study the streamwise vortex at various VG angles using fluent. So far ive been using the SST k-w model which has been performing well and giving me good convergence. Im using SIMPLE coupling and second order methods and converging down to 1e-5.

This is mirroring an experimentation that is still being carried out so i do not have experimental data as yet to validate my simulations. Do you experts out there think SST k-w is suitable for vortex simulation? or are there any other parameters i can change to enhance this?

RSM or LES is out of the question for me. I've also tried RNG k-epsilon which has been giving me very bad convergence issues even though standard k-epsilon performs well. Im using snappyHexMesh for my meshing and have high density around and downstream of the VG.

Any advice would be much appreciated. Thanks in advance for help! i wouldn't have even got this far if it wasn't for this site!!

Hardeep

Hardeep · July 22, 2013, 07:16

I have since tried the Realizable k-epsilon model and the results look good. The vortex is far less diffused compared to standard k-e, and quite close to what im getting with SST k-w, with the added advantage that it converges in half the time. I'm now really interested to try the RNG k-e model as i know it's suited to swirling flows. Any ideas why the RNG model is not converging when all other models converge well?? The continuity residual just flat lines at 1e-2 and k oscillates sharply. I'm using the same mesh for all of them with approx. 6m cells and 30<y+<300.

Please any advice/thoughts would be appreciated! Thank you

July 21, 2013, 10:52	Vortex generators using fluent	#1
Hardeep New Member Hardeep Join Date: Dec 2011 Posts: 4 Rep Power: 14	Hi guys, Im fairly new to CFD. I've been trying to model a triangular vortex generator (VG) placed on a baseboard in the middle of a flow to study the streamwise vortex at various VG angles using fluent. So far ive been using the SST k-w model which has been performing well and giving me good convergence. Im using SIMPLE coupling and second order methods and converging down to 1e-5. This is mirroring an experimentation that is still being carried out so i do not have experimental data as yet to validate my simulations. Do you experts out there think SST k-w is suitable for vortex simulation? or are there any other parameters i can change to enhance this? RSM or LES is out of the question for me. I've also tried RNG k-epsilon which has been giving me very bad convergence issues even though standard k-epsilon performs well. Im using snappyHexMesh for my meshing and have high density around and downstream of the VG. Any advice would be much appreciated. Thanks in advance for help! i wouldn't have even got this far if it wasn't for this site!! Hardeep

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July 22, 2013, 07:16		#2
Hardeep New Member Hardeep Join Date: Dec 2011 Posts: 4 Rep Power: 14	I have since tried the Realizable k-epsilon model and the results look good. The vortex is far less diffused compared to standard k-e, and quite close to what im getting with SST k-w, with the added advantage that it converges in half the time. I'm now really interested to try the RNG k-e model as i know it's suited to swirling flows. Any ideas why the RNG model is not converging when all other models converge well?? The continuity residual just flat lines at 1e-2 and k oscillates sharply. I'm using the same mesh for all of them with approx. 6m cells and 30<y+<300. Please any advice/thoughts would be appreciated! Thank you