Force function gives a negative value.

kyo022 · November 29, 2017, 02:02

Hello,

I'd like to ask what is wrong with my CFD result on CFD-Post, since I keep getting negative values when I try to calculate the force applied on the body to obtain the drag force.

I believe I've tried different boundary conditions for several times, and the mesh quality looks okay according to the value of the skewness.

The details are shown in the attached picture.

I would appreciate if anyone advise on this.

Have a great day.

Eric.

JuPa · November 29, 2017, 08:52

The negative sign is showing direction with respect to your coordinate frame.

Force is a vector. It can be positive or negative.

In your case it is 1.13 N in the negative x direction.

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November 29, 2017, 08:52		#2
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 14	The negative sign is showing direction with respect to your coordinate frame. Force is a vector. It can be positive or negative. In your case it is 1.13 N in the negative x direction.