# inlet velocity profiles

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 August 13, 2002, 14:50 inlet velocity profiles #1 cfxuser Guest   Posts: n/a Sponsored Links hi, I want to calculate a swirling pipe flow with a specified inlet velocity profile of the type U_ax=f(r) W_tan=f(r) The profile is not an expression but stored in a file in cylindrical coordinates: r_1 u_1 w_1 r_2 u_2 w_2 etc. The geometry is set up so that that the x-axis is the axis of rotation. So the radius would be calculated as r=sqrt(y^2 + z^2). Now my problem is: Is it sufficient to define a new variable "rad" with CEL so that the solver "knows" that the tabulated values are cylindrical ? Thanks for your comments

 August 14, 2002, 17:07 Re: inlet velocity profiles #2 Neale Guest   Posts: n/a You will need to define u, v and w velocity components from your radial and axial components. This requires transforming your cylindrical components into Cartesian in CEL. You could do this with 1D interpolation functions and the following: CEL: EXPRESSIONS: r = sqrt(x^2+y^2) theta = atan(y,x) Vrad = Vradf(r) Vaxial = Vaxialf(r) Vtheta = Vthetaf(r) Ucomp = Vaxial Vcomp = Vradial*cos(theta) + r*Vtheta*sin(theta) Wcomp = Vradial*sin(theta) - r*Vtheta*cos(theta) END END where Vradf, Vaxialf, and Vthetaf are 1D interpolation functions for each of your velocity components. Looks like you might need to split your text files up. Hopefully I got my sin() and cos() correct!

 August 26, 2002, 14:13 Re: inlet velocity profiles #4 Neale Guest   Posts: n/a From this I can't tell. Is there any more output in the output file which is more descriptive than what you have? One thing you should be able to do is set Ucomp = Vaxiaf(rad) directly, rather than through another expression variable. I'm also not sure why you have created a user function called "Ucomp". This should not be necessary. All you should need is to define three user functions: Vradialf, Vaxialf and Vthetaf and set Ucomp, Vcomp and Wcomp accordingly. Maybe this is/was the problem? Neale

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