moment defining

mht · December 31, 2011, 02:53

hello everyone：
I want to know how Fluent define the Moment Coefficient, Was it defined as: cm=M/(0.5*density*v*v)? or someelse form.

thanks a lot!

duri · December 31, 2011, 05:41

cm=M/(0.5*density*area*length*V*V), all taken from reference values.

mht · January 3, 2012, 21:12

Duri,thanks for your attention
now,I have known that cm=M/(0.5*density*area*length*V*V), and all taken from reference values. I also use Fluent Function compute_force_and_moment to get the moment,then i used the moment to get cm, I found that this cm was diffenent from the Monitors-Force-CM, Could you tell me why?

duri · January 4, 2012, 12:29

It will be same. Check moment origin, axis etc.

mht · January 5, 2012, 03:18

I think i have misused this function, could you give me a UDF that contains this function, thank you very much!

December 31, 2011, 02:53	moment defining	#1
mht New Member mohongtao Join Date: Dec 2011 Posts: 5 Rep Power: 14	hello everyone： I want to know how Fluent define the Moment Coefficient, Was it defined as: cm=M/(0.5densityv*v)? or someelse form. thanks a lot!

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December 31, 2011, 05:41		#2
duri Senior Member duri Join Date: May 2010 Posts: 245 Rep Power: 16	cm=M/(0.5densityarealengthV*V), all taken from reference values.

January 3, 2012, 21:12		#3
mht New Member mohongtao Join Date: Dec 2011 Posts: 5 Rep Power: 14	Duri,thanks for your attention now,I have known that cm=M/(0.5densityarealengthV*V), and all taken from reference values. I also use Fluent Function compute_force_and_moment to get the moment,then i used the moment to get cm, I found that this cm was diffenent from the Monitors-Force-CM, Could you tell me why?

January 4, 2012, 12:29		#4
duri Senior Member duri Join Date: May 2010 Posts: 245 Rep Power: 16	It will be same. Check moment origin, axis etc.

January 5, 2012, 03:18		#5
mht New Member mohongtao Join Date: Dec 2011 Posts: 5 Rep Power: 14	I think i have misused this function, could you give me a UDF that contains this function, thank you very much!