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January 9, 2005, 09:25 
Help!trasient inlet user subroutine

#1 
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Dear sirs,
I want to compute a problem with transient inlet, but I do not know how to solve it in subroutine. The boundary condition equation is descirbed as follow: U=cosh(Y)*cos(XTIME) V=sinh(Y)*sin(XTIME) here, Y=03,X=08 How can I compile it in inlet subroutine ?And how to I define the run time in user subrotine? Can anybody help me in detail?Thank you in advance. 

January 10, 2005, 06:04 
Re: Help!trasient inlet user subroutine

#2 
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One suggestion for computing the time is to compute it in the soubroutine as: ITER*timestep ITER: is the iteration number provided by STAR timestep: the one you are using
in the soubroutine you have the coordinates of the cells at the boundaries so you can use those for the function you planning to use To find out the name of the variables used in STAR check the file nom.inc and usrdat.inc good luck 

January 11, 2005, 03:34 
Re: Help!trasient inlet user subroutine

#3 
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well,
in user routine bcdefi.f specify these equations, as you put it in your question here. the star will understand U,V,W as velocities, UCL,VCL,WCL are velocities in given local coord. system. TIME is time in the simulation, so there is the way how to input time in your simulation through the TIME variable. In star GUI specify, that the inlet is given by "user define" run star, it will compile it and run the case.... matej 

January 11, 2005, 20:19 
Re: Help!trasient inlet user subroutine

#4 
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Dear matej,
Thank you for your kindness.Yet I still have a question here:How can I define Y from 03 and X from 08,here 3 is not YMax?And the water surface is varying with time(a kind of sine wave),how can I describe it in starcd ?Thank you ! 

January 12, 2005, 10:40 
Re: Help!trasient inlet user subroutine

#5 
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Dear matej, In starcd, can I let U(i,j,k) to be the velocity at everywhere?And let X(i) represent X values of every cell? Thanks


January 12, 2005, 14:00 
Re: Help!trasient inlet user subroutine

#6 
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if X.ge.0 and X.le.8 and Y .....
U=cosh(Y)*cos(XTIME) V=sinh(Y)*sin(XTIME) ENIF if you write this with the correct syntax it should work. 

January 13, 2005, 21:13 
Re: Help!trasient inlet user subroutine

#7 
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Dear Jörn Beilke ,
At the boundary,here,X is a constant,the velocity is only varying with Y and TIME,do we should define it as you said ( if X.ge.0 and X.le.8 and Y ..... )? In starcd ,do X,Y,Z represent array X(i),Y(i),Z(i)?And in my question, the water surface is moving like Sine wave, how can we indicate it? Is the velocity at the boundary is needed enough? 

January 14, 2005, 03:30 
Re: Help!trasient inlet user subroutine

#8 
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HI,
I'm not sure I do follow what you want to do. In first post you said, that the X and Y (coordinates) are changing Y=03,X=08. In your last post, you said, that X is constant. bit puzzling, but anyway. If X is not changing, or is not coordinate which you said is changing from 08, you do not need to put if X.ge.0 and X.le.8 in the IF condition. Yes, you're right  X and Y and Z are coordinates in star routine. the water stuff: Do I understand correctly you model twophase flow with water and some gas, and you want to have the watergas interface going through the inlet, and you want to specify the waves of the surface on the inlet? matej 

January 14, 2005, 09:31 
Re: Help!trasient inlet user subroutine

#9 
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Dear matej,
Thank you first! Yes ,you are right,I am modeling twophase flow with water and air ( ocean wave motion ),and want to specify the waves of the surface on the inlet. How can I make it? My problem is twodimension ocean wave of XY coodinate.Is the velocity at the boundary is enough,or anything else needed? yours,sincerely 

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