How to calculate drag forces?

rail118 · October 28, 2014, 14:56

Good afternnon,

First of all, sorry for my limited knowledge. I've just three days working with Flow3D.

I have a solid in .STL format, and I want to calculate the drag force of this solid, but I can't find the tool to calculate it.

I did some simulations and I calculated the pressure, velocity magnitude... but I don't know how calculate drag forces. I don't know if I have to activate some options in Physics or Meshing&Geometry...

I hope your answers.

Thanks in advance

R

aoz · October 30, 2014, 11:47

You should select "Pressure and Shear Force" and "Wetted Area" outputs from

Meshing&Geometry>Component Properties>Component # > Output > click them and run simulation,

Then go to Analyze tab,

Analyze > Probe > General history > Select Component1 Fluid Force and render.

rail118 · October 30, 2014, 13:14

Why should I click integrate option? is not drag force= component1 fluid force= pressure+shear ??

If I click only component1 fluid force= pressure+shear wihout any click, the graph becomes constant over time, so I would have the force value, but if I click integrate option, the graph is rising over time.

What is the real value of drag force?

aoz · October 30, 2014, 13:45

Sorry for confusion

.

The Pressure Force values are already integrated values over area.

The "integrate" option is for time integral of value.

So,dont use integrate option, use "component1 fluid force" value.

October 28, 2014, 14:56	How to calculate drag forces?	#1
rail118 New Member Oscar Join Date: Oct 2014 Posts: 2 Rep Power: 0	Good afternnon, First of all, sorry for my limited knowledge. I've just three days working with Flow3D. I have a solid in .STL format, and I want to calculate the drag force of this solid, but I can't find the tool to calculate it. I did some simulations and I calculated the pressure, velocity magnitude... but I don't know how calculate drag forces. I don't know if I have to activate some options in Physics or Meshing&Geometry... I hope your answers. Thanks in advance R

October 30, 2014, 11:47		#2
aoz New Member Join Date: Feb 2014 Posts: 2 Rep Power: 0	You should select "Pressure and Shear Force" and "Wetted Area" outputs from Meshing&Geometry>Component Properties>Component # > Output > click them and run simulation, Then go to Analyze tab, Analyze > Probe > General history > Select Component1 Fluid Force and render. Last edited by aoz; October 31, 2014 at 04:29.

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October 30, 2014, 13:14		#3
rail118 New Member Oscar Join Date: Oct 2014 Posts: 2 Rep Power: 0	Why should I click integrate option? is not drag force= component1 fluid force= pressure+shear ?? If I click only component1 fluid force= pressure+shear wihout any click, the graph becomes constant over time, so I would have the force value, but if I click integrate option, the graph is rising over time. What is the real value of drag force?

October 30, 2014, 13:45		#4
aoz New Member Join Date: Feb 2014 Posts: 2 Rep Power: 0	Sorry for confusion . The Pressure Force values are already integrated values over area. The "integrate" option is for time integral of value. So,dont use integrate option, use "component1 fluid force" value.