# Calculation Hidrodynamic & Aerodynamic Lift

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 January 4, 2021, 16:34 Calculation Hidrodynamic & Aerodynamic Lift #1 New Member   ali_Ebrahimi Join Date: Jan 2021 Posts: 9 Rep Power: 5 Hi I work in the field simulation CFD high speed planing in STAR CCM+. I want to calculate Hydrodynamic & Aerodynamic Liftseparately in multiphase flow (water & Air). Do you suggest a way to do this?

 January 7, 2021, 05:46 #2 Senior Member   Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20 this is easy using a new threshold with the part surface you require forces measured on as the input part, the scalar field function set to the volume fraction of water or air, and the range 0,.5 or .5,1 depending on which field is chosen. this creates a new derived part which is a subset of the chosen input part and you do your force calcs on this new part

January 8, 2021, 03:03
#3
New Member

ali_Ebrahimi
Join Date: Jan 2021
Posts: 9
Rep Power: 5
Quote:
 Originally Posted by ping this is easy using a new threshold with the part surface you require forces measured on as the input part, the scalar field function set to the volume fraction of water or air, and the range 0,.5 or .5,1 depending on which field is chosen. this creates a new derived part which is a subset of the chosen input part and you do your force calcs on this new part
I have done these processes before and the answer was not correct.
However, the sum of the aerodynamic and hydrodynamic lift forces calculated from the threshold will not be equal to the total lift force calculated from the part region.
I share photos of the settings made.

Last edited by ali_ebrahimi; January 8, 2021 at 09:51.

 January 8, 2021, 04:50 #4 Senior Member   Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20 check the threshold parts in a geometry scene to make sure your threshold subsets of those surfaces are correct since it looks to me like you have used .05 instead of 0.5 ali_ebrahimi likes this.

 Tags cfd analysis, high speed planing, lift force, star ccm+