Shaking a Can under changing gravity
 

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Hi Community

I have a special problem and maybe someone might help me and(or) write me a UDF. I have a Can with fluid domain inside and further is heated up from outside in a process. Additional the Can is now shaked to increase heat transfer and "forced convection"

Question: I have the acceleration function a= w^2*sin(w*t) w(omega)= 17.6 1/s f.e

so under gravity-panel:

y-direction a = 9.81 m/s^2

x-direction: a=17.6^2*sin(17.6*t)

I found nothing in the input-box for ...(t), so for unsteady calculation a udf is needed. Can someone write that short case

Found nothing in help or search.Would be happy abou any help

Thy Optixxx

Re: Shaking a Can under changing gravity
 

Dear kenischi: Have your read fluent tutorial no. 15 for using VOF model. It would ontain usefull information for your case. I can send you the case file if needed. regards

Re: Shaking a Can under changing gravity
 

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Thx Medi for help

Yes in case of domain splitting liquid/gas you are right, because the can has also a headspace of air which can´t be neglegted. So the VOF model is needed, additional the heat equation.

But for moving walls you can only set constant velocity numbers and that isn´t the case. The can is shaked translational (like a piston over a crankshaft)with changing velocities and accerelation over time. So the wall is accerlerated and then liquid and gas too. Therefore i´m sure, this can only be done with an udf, that calculates acceleration every time step, because we have a(t)=....sin(wt). Btw w (omega) is the rotational velocity of the crankshaft. So i need the udf for wall acceleration in wall panel

Has anyone some further ideas

Thx anyway

Optixxx

Re: Shaking a Can under changing gravity
 

You can effectively change the values of gravity components during flow time via an udf or a scheme file. I personally use the second choice. Let me know if you are interested in it. Advantages: you don't need to compile or interpret it. Disadvantage: you have to write an input file that fluent have to read any time step.

Edi.

Re: Shaking a Can under changing gravity
 

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Thx Edi

for your advice, but i don´t need changing accerleration or velocities in define/conditions, because only the Can get that, inside the Can Fluent calculates swapping over viscosity. The liquid isn´t affected. So i need the wall-panel. Also i can calculate changing velocities over time for the wall, but under moving wall i normally able to set constant speed

Any hints how i can changing velosity, maybe UDF

thx Optixxx