one-way vs two-way FSI for stall deformation of a hydrofoil

Kina · February 7, 2014, 14:00

Hello,
I am currently comparing the flow around a hydrofoil for a rigid body (CFD) and an elastically deformable body (FSI). As my computer takes a very long time getting results I asked myself if it would be possible to go for a one-way FSI and then simply remesh the deformed model and rerun the CFD again with a "rigid deformed model". This seems to be about accurate for regular deformation. However, when it comes to stall the pressure on the foil decreases and the deformation also decreases with it. When I now rout back the deformation to the CFD interface, wouldn't that cause huge errors? I am just wondering because I have not found any data on that topic.

Thank you!
Alex

Totalsim · February 8, 2014, 12:01

I think it all depends upon the amount of deformation that is occurring and its effect upon the flow.

It may be that the deformation is relatively small and doesn't significantly affect the flow regime. Conversely if the deformation is capable of causing stall etc then it needs a more tightly coupled solution.

Kina · February 8, 2014, 13:03

As I am dealing with fiberglass, I have tip deformations of about 19mm for a length of rougly 240mm. So the deformation is quite large. My initial thought was that in the presence of stall, the initial deformation for the first coupling step might be not that large but as soon as the foil tip deforms, it recovers from stall and develops a higher pressure that is not captured in a simple "i put pressure data in fea and run cfd for the deformed mesh". I am still not sure, but that's the way I imagine it.

February 7, 2014, 14:00	one-way vs two-way FSI for stall deformation of a hydrofoil	#1
Kina Senior Member Alex Join Date: Jan 2014 Posts: 126 Rep Power: 12	Hello, I am currently comparing the flow around a hydrofoil for a rigid body (CFD) and an elastically deformable body (FSI). As my computer takes a very long time getting results I asked myself if it would be possible to go for a one-way FSI and then simply remesh the deformed model and rerun the CFD again with a "rigid deformed model". This seems to be about accurate for regular deformation. However, when it comes to stall the pressure on the foil decreases and the deformation also decreases with it. When I now rout back the deformation to the CFD interface, wouldn't that cause huge errors? I am just wondering because I have not found any data on that topic. Thank you! Alex

February 8, 2014, 12:01		#2
Totalsim Member Jon Join Date: Mar 2013 Posts: 47 Rep Power: 13	I think it all depends upon the amount of deformation that is occurring and its effect upon the flow. It may be that the deformation is relatively small and doesn't significantly affect the flow regime. Conversely if the deformation is capable of causing stall etc then it needs a more tightly coupled solution. __________________ TotalSim CFD Engineer www.totalsimulation.co.uk

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February 8, 2014, 13:03		#3
Kina Senior Member Alex Join Date: Jan 2014 Posts: 126 Rep Power: 12	As I am dealing with fiberglass, I have tip deformations of about 19mm for a length of rougly 240mm. So the deformation is quite large. My initial thought was that in the presence of stall, the initial deformation for the first coupling step might be not that large but as soon as the foil tip deforms, it recovers from stall and develops a higher pressure that is not captured in a simple "i put pressure data in fea and run cfd for the deformed mesh". I am still not sure, but that's the way I imagine it.