How to convert a coordinate system into a position vector?

arm593 · July 31, 2020, 07:09

I want to use this coordinate system's origin as the center of an object and then compute moments occurring on the faces of this object relative to the origin.

For this I thought of multiplying the force vectors by the position vector resulting from this coordinate system. Is it possible to do this in Star CCM+?

ping · July 31, 2020, 09:59

it is much simpler than that since you have the moment report built in which has properties to allow you to set the csys and the part(s) to measure on

cwl · July 31, 2020, 10:25

Also - in case of necessity you can set your own coordinate system.

arm593 · July 31, 2020, 11:41

I have tried the built-in reports but they give wrong results in comparison to the Literature. I am dealing with an open channel flow where I am trying to compute the moments due to the hydrodynamic forces of the water.

From my simulations I understand the built-in functions consider both hydrostatic and hydrodynamic forces, and I only require the hydrodynamic component. So I created a vector field function for the hydrodynamic force as explained on a different post in this forum.

However, when it comes to the moment I am unable to get the right approach, so I thought that by multiplying this vector force by the position vector would give me the moments about the center of the object.

ping · August 1, 2020, 00:29

well unless you are using the moment report incorrectly i suspect your model has a problem since i've never had a moment report lie.
but it is not hard to create your own moment report using the force vector field and the radial component of a local cylindrical csys you create at your required axis.

July 31, 2020, 07:09	How to convert a coordinate system into a position vector?	#1
arm593 New Member A. Mier Join Date: Jun 2020 Posts: 3 Rep Power: 6	I want to use this coordinate system's origin as the center of an object and then compute moments occurring on the faces of this object relative to the origin. For this I thought of multiplying the force vectors by the position vector resulting from this coordinate system. Is it possible to do this in Star CCM+?

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July 31, 2020, 09:59		#2
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	it is much simpler than that since you have the moment report built in which has properties to allow you to set the csys and the part(s) to measure on

July 31, 2020, 10:25		#3
cwl Senior Member Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 437 Rep Power: 18	Also - in case of necessity you can set your own coordinate system.

July 31, 2020, 11:41		#4
arm593 New Member A. Mier Join Date: Jun 2020 Posts: 3 Rep Power: 6	I have tried the built-in reports but they give wrong results in comparison to the Literature. I am dealing with an open channel flow where I am trying to compute the moments due to the hydrodynamic forces of the water. From my simulations I understand the built-in functions consider both hydrostatic and hydrodynamic forces, and I only require the hydrodynamic component. So I created a vector field function for the hydrodynamic force as explained on a different post in this forum. However, when it comes to the moment I am unable to get the right approach, so I thought that by multiplying this vector force by the position vector would give me the moments about the center of the object.

August 1, 2020, 00:29		#5
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	well unless you are using the moment report incorrectly i suspect your model has a problem since i've never had a moment report lie. but it is not hard to create your own moment report using the force vector field and the radial component of a local cylindrical csys you create at your required axis.