PatchIntegrate vs. forces functions

kimou · January 7, 2021, 08:33

Hello everybody,

I am trying to calculate the forces on the surface of a cylinder emerged in a stream of water. I use the FORCES function I find: (-1.305747 1.757018e-18 42.25548) and with patchIntegrate: 308.3666

Can you explain to me dear users why a factor of ~ 8 between the two methods?

thank you in advance

best regrets

PenPencil · January 15, 2021, 11:35

Hi,

I guess when you post-process with patchIntegrate some parameters are assumed by default. On the other hand, by using the 'forces' functionObject, you're obliged to give some parameters in your controlDict, such as density and area. If you could provide more info, perhaps we would be able to be more assertive.

HPE · January 15, 2021, 16:35

maybe related?: https://develop.openfoam.com/Develop...m/-/issues/787

January 7, 2021, 08:33	PatchIntegrate vs. forces functions	#1
kimou New Member H.Ham Join Date: Mar 2019 Posts: 21 Rep Power: 7	Hello everybody, I am trying to calculate the forces on the surface of a cylinder emerged in a stream of water. I use the FORCES function I find: (-1.305747 1.757018e-18 42.25548) and with patchIntegrate: 308.3666 Can you explain to me dear users why a factor of ~ 8 between the two methods? thank you in advance best regrets

January 15, 2021, 16:35		#3
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 932 Rep Power: 12	maybe related?: https://develop.openfoam.com/Develop...m/-/issues/787 __________________ 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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January 15, 2021, 11:35		#2
PenPencil New Member Icaro Amorim de Carvalho Join Date: Dec 2020 Posts: 24 Rep Power: 5	Hi, I guess when you post-process with patchIntegrate some parameters are assumed by default. On the other hand, by using the 'forces' functionObject, you're obliged to give some parameters in your controlDict, such as density and area. If you could provide more info, perhaps we would be able to be more assertive.