wallShearStress function object for single phase transport models only?

JM27 · April 10, 2020, 11:15

Hi,

I am running a two-phase simulation and I use the wallShearStress functionObject to plot the wall shear stress distribution on wall boundaries.

The flow is laminar and compressible, so my question is, does the wallShearStress functionObject in OpenFOAM work for my case or is it meant for single phase transport models only?

I've read elsewhere in this forum that the wallShearStress function yields incorrect results for multiphase flows.

The units of the WSS I obtain are in Pascal however they seem to be underestimated.

I'd be very grateful to anyone who shares their knowledge

HPE · April 10, 2020, 14:32

wallShearStress can work for multiphase flows as well - is it possible to provide a MWE where it does not work properly?

JM27 · April 14, 2020, 08:12

Hi HPE

Thanks for your reply

Unfortunately I cannot provide a MWE that proves this, however I have been trying to compare my results obtained using wallShearStress function object with existing results in literature. The maximum WSS due to jetting is expected to reach 100kPa but the maximum in my simulations is only a fraction of that

Do you know how I can calculate the wall shear stress in my simulations without using this function? It would be a good exercise to compare results using two alternative approaches.

HPE · April 14, 2020, 09:13

Don't know, sorry. But might be good to pay attention to the proper normalisation of the wallShearStress? May be that would be the problem? Otherwise, I don't think this FO has some type of bug.

JM27 · April 14, 2020, 10:15

Hi HPE,

I'm not sure I understand what you mean by proper normalisation of the wallShearStress - could you explain further, please?

Thanks!

April 10, 2020, 11:15	wallShearStress function object for single phase transport models only?	#1
JM27 Member Join Date: Apr 2018 Location: UK Posts: 78 Rep Power: 8	Hi, I am running a two-phase simulation and I use the wallShearStress functionObject to plot the wall shear stress distribution on wall boundaries. The flow is laminar and compressible, so my question is, does the wallShearStress functionObject in OpenFOAM work for my case or is it meant for single phase transport models only? I've read elsewhere in this forum that the wallShearStress function yields incorrect results for multiphase flows. The units of the WSS I obtain are in Pascal however they seem to be underestimated. I'd be very grateful to anyone who shares their knowledge

April 10, 2020, 14:32		#2
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 931 Rep Power: 13	wallShearStress can work for multiphase flows as well - is it possible to provide a MWE where it does not work properly? __________________ The OpenFOAM community is the biggest contributor to OpenFOAM: User guide/Wiki-1/Wiki-2/Code guide/Code Wiki/Journal Nilsson/Guerrero/Holzinger/Holzmann/Nagy/Santos/Nozaki/Jasak/Primer Governance Bugs/Features: OpenFOAM (ESI-OpenCFD-Trademark) Bugs/Features: FOAM-Extend (Wikki-FSB) Bugs: OpenFOAM.org How to create a MWE New: Forkable OpenFOAM mirror

April 14, 2020, 09:13		#4
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 931 Rep Power: 13	Don't know, sorry. But might be good to pay attention to the proper normalisation of the wallShearStress? May be that would be the problem? Otherwise, I don't think this FO has some type of bug. __________________ The OpenFOAM community is the biggest contributor to OpenFOAM: User guide/Wiki-1/Wiki-2/Code guide/Code Wiki/Journal Nilsson/Guerrero/Holzinger/Holzmann/Nagy/Santos/Nozaki/Jasak/Primer Governance Bugs/Features: OpenFOAM (ESI-OpenCFD-Trademark) Bugs/Features: FOAM-Extend (Wikki-FSB) Bugs: OpenFOAM.org How to create a MWE New: Forkable OpenFOAM mirror

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April 14, 2020, 08:12		#3
JM27 Member Join Date: Apr 2018 Location: UK Posts: 78 Rep Power: 8	Hi HPE Thanks for your reply Unfortunately I cannot provide a MWE that proves this, however I have been trying to compare my results obtained using wallShearStress function object with existing results in literature. The maximum WSS due to jetting is expected to reach 100kPa but the maximum in my simulations is only a fraction of that Do you know how I can calculate the wall shear stress in my simulations without using this function? It would be a good exercise to compare results using two alternative approaches.

April 14, 2020, 10:15		#5
JM27 Member Join Date: Apr 2018 Location: UK Posts: 78 Rep Power: 8	Hi HPE, I'm not sure I understand what you mean by proper normalisation of the wallShearStress - could you explain further, please? Thanks!