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-   -   specifying:G(transfo_matrix) in dynamesh_CG_MOTION (https://www.cfd-online.com/Forums/fluent/31454-specifying-g-transfo_matrix-dynamesh_cg_motion.html)

calogero May 11, 2003 13:54

specifying:G(transfo_matrix) in dynamesh_CG_MOTION
 
Hi everybody! I have to specify an scillating movement of an airfoil using the CG_MOTION macro. the angle of incidence of the airfoil is a sine-like function.-step-1: I derived it (analytically)in order to specify the angular velocity of the foil (I set only angular velocity of the foil about 1/3 chord length) at this step: am i right using this macro or i'd better use anothe one? and am i right using the angle of incidence derivative as the angular velocity of the foil? -step-2: fluent uses the following formula in order to update the angle of incidence of the foil:<> (theta_i+1 = (theta_i)+ G*omega*timestep) see fluent_UG.section.9.6.4: http://www.psc.edu/general/software/...ug/node392.htm with omega= the angular velocity that i set to be theta_derivative<> and G: a transformation matrix to specify!! I modeled in excel the movement with the original theta sine-like formula, superposed to the fluent formula without G: i found a difference of amplitude and phase!! that means I need to specify G in the CG_MOTION macro in order to describe the right movement for fluent!how to do so???? thanx for any help



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