Centrifugal fan

[ZachJa]

Hello,

thank you,
I removed mesh joining from turbo-machinery into meshes selection. Simulation goes a little bit further but still have an error:
Some boundary condition definitions are incomplete or incorrect.
For details, read the end of the calculation log,
or visualize the error postprocessing output.
Error.med looks like the following:
https://www.dropbox.com/s/p7v9gi07opldjvy/error?dl=0
Seems, that smth is wrong with stator joining face that initially is not in contact with rotor. Could it be mesh issue? or smth else?

[Yvan Fournier]

Hello,

Yes, this is exactly what I told you in the previous message : you need to check your boundary conditions ad joining criteria (comparing post-processing of mesh groups from a "check mesh" stage and the boundary condition error is the easiest way).

Regards,

Yvan

[ZachJa]

Thank you,

could you please specify:
when I use cyclic simulation (1 blade of wheel which consists of 8 blades ie 45 deg circular symmetry) and I define inlet conditions as 1 m3/s - is it per 1 blade? or for full wheel?

[Yvan Fournier]

Hello,

The boundary conditions apply to whatever portion of the geometry you represent in your mesh.

When in doubt, I recommend simply trying things, and postprocessing to determine how the code actually did things (much faster than waiting or an answer from somebody else).

Regards,

Yvan

[ZachJa]

Thank you!
looks like it works per segment as you stated it.
I am wondering: is it possible to set variable instead of fixed value at inlet boundary condition? ie now I have frozen rotor setup with 1 m3/s at inlet which is constant during whole 10 s period, but I would like to have non-fixed (from 0 to 1 m3/s for instance) value at inlet, is it possible with frozen rotor setup?

[Yvan Fournier]

Hello,

Yes, you can set a variable inlet condition using either a mathematical expression (in the GUI; look ao the "predefined symbols" list in the user profile) or the cs_user_boundary_conditions.f90 user subroutine.

Regards,

Yvan

[ZachJa]

Thank you!
I am trying to define volumic flow rate using user law.
so: q_v = (function)dt, but I am not sure how to set function which is from 0.1 to 1 m3/s?
I tried:
a = 0.1;
b = 1;
q_v = (a,b)dt;
but it does not work...

[Yvan Fournier]

Hello,

Did you check the MEI syntax examples ? They contain the "t" variable, which should be useful to you.

Regards,

Yvan

[ZachJa]

Hello,
yes, I was looking for MEI syntax examples, but unfortunately, could not find anything concretely...
Could you please specify where to look for (may be link), or kind of debian math library should be installed?

[Yvan Fournier]

Hello,

There is no relation between MEI and a Debian math library. In the GUI, where you define MEI expressions, there are tabs providing the list of defined symbols and examples. The syntax is otherwise almost the same as C, except for the "modulo" function where "a%b" in C is replaced by "mod(a,b)" in MEI.

Regards,

Yvan