# Anyone knows?

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 June 30, 2004, 10:56 Anyone knows? #1 Panos Guest   Posts: n/a Hi everyone. In order to calculate aerodynamic coefficients do I have to use the standard formulas or STAR has the abillity to calculate them for a two dimensional body, say an airfoil? Thank you in advance

 June 30, 2004, 11:26 Re: Anyone knows? #2 Jörn Beilke Guest   Posts: n/a You can calculate whatever you want in prostar. Have a look at: http://www.adapco-online.com and special http://www.adapco-online.com/adapco_...t/drpost9.html

 July 1, 2004, 07:54 Re: Anyone knows? #3 Panos Guest   Posts: n/a I tried that but I get very large values for aerodynamic coefficients. In AREF I put the chord lenth of the airfoil multiplied by the width of my model since I have a three-dimensional mesh. Is it correct? Again thanx

 July 1, 2004, 11:14 Re: Anyone knows? #4 Jörn Beilke Guest   Posts: n/a Are you sure that all the units have the same dimension? Maybe your area is mm^2 instead of m^2. type *list AREA to get the value and compare it with the reality.

 July 1, 2004, 12:18 Re: Anyone knows? #5 Panos Guest   Posts: n/a Jorn all my units have the same dimension, SI. Can't I just use the standard formulas? for example divide the lift force that i get from the *.erd file with density,velocity of free stream and area which is the chord lenth times the length of the computational domain in the z-direction. When I load the wall data and try to plot them it sais that no wall data plotted. Again I really appreciate it.

 July 1, 2004, 14:38 Re: Anyone knows? #6 4xF Guest   Posts: n/a Remember also that pro-STAR models are in meters and that the data calculated by STAR takes the scaling factor into account. Have you also checked that out?

 July 2, 2004, 06:34 Re: Anyone knows? #7 Panos Guest   Posts: n/a I know that pro-satr models are in meters but I did not know that Star takes the scaling factor into account. What exactly you mean by that? Again thanx a lot.

 July 2, 2004, 08:18 Re: Anyone knows? #8 4xF Guest   Posts: n/a I mean that when you scale the model (up or down) for the simulations, STAR takes this value for the simulations. If your model has a chord length of 0.1m in pro-STAR and you use a geometrical factor of 20 when you write the geometry for STAR, the solver will run a simulation with a model 20 times bigger in size. This will result in another flow and in different/bigger forces. If calculate Cd and Cl, you have to take that into account,

 July 2, 2004, 09:07 Re: Anyone knows? #9 Panos Guest   Posts: n/a Actually the chord lenth is 1 m when I make the geometry. But I am interested in what you sais. How do you introduce the scale factor when you write the geometry. Thanx for your patience

 July 2, 2004, 14:41 Re: Anyone knows? #10 4xF Guest   Posts: n/a Scaling down to millimeters: GEOM,,0.001

 July 8, 2004, 22:25 Re: Anyone knows? #11 steve Guest   Posts: n/a No I think you are wrong. The scale factor is used to translate prostar model coords INTO meters. If you model in prostar mm, then the scale factor must be .001. The data in STAR MUST be meters or you will not get a correct answer. You cannot scale down meters in prostar to mm in STAR.