|December 22, 2010, 20:02||
How to find center of pressure
Join Date: Nov 2010
Posts: 5Rep Power: 6
I've done a simulation of a sample car body, and I would like to evaluate the distribution of aerodynamic forces between front and rear of the car.
To do so I need to know the position of the center of pressure.
I've read in this forum and it seems that with Fluent you can do this simply with a report, I couldn't find nothing similar in Star-ccm. Is it right?
In a previous post I've found that you can use the surface integral report to calculate the coordinates.
I've defined three user field functions like this:
$$Position*$Pressure (for X direction)
surface integrated this and divided by the surface integral of Pressure.
I've found three coordinates that seems good, but if I calculate a moment defining this coordinates as origin of my axis I found non zero moments as expected.
What is wrong?
There's a simpler procedure to find the center of pressure location?
Thank you everybody for your help.
|February 11, 2011, 12:21||
Join Date: Nov 2010
Posts: 2Rep Power: 0
I have a similar problem, how is this calculated by hand, I have a Moment about Y (horizontal) and a Force in X (drag longitudinal) and Z (lift vertical). This gives me an equation with two unknowns in (the distance x and z from the origin that the forces act).
Drag*z - Lift*x = Moment
Is this right? How can the two unknowns be solved?
|February 16, 2011, 10:52||
Join Date: Jul 2010
Posts: 11Rep Power: 6
You create a Momentum coefficient report.
As the Axis Origin you use e.g. the front tire.
As the Reference Radius you use the distance between front and back tire.
You don't need to know the center of mass or pressure since you cut at the tires.
That is the momentum doesn't act around the the center of mass or pressure, but around the front tire's contact with the ground
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