[HOW TO] solve the velocity components (Ux and Uy) from 2 equations

Kummi · January 17, 2020, 12:13

Hello Foamers,
Based on my previous thread, I'm continuing this new thread !!
Couldn't able to figure out the technique - NO problem with Compilation
I have defined a volVectorField U with two scalar fields Ux and Uy along x and y directions (2D). I want to extract Ux and Uy based on two equations given below.

Quote:

$\left [ \frac{\delta v_{y}}{\delta {x}}-\frac{\delta v_{x}}{\delta {y}} \right ] - \left \{ v_{x} \left [ \frac{\delta}{\delta {y}}(ln(f_{1}+f_{2}\left | \rho v_{x} \right |) \right ] -v_{y} \left [ \frac{\delta}{\delta {x}}(ln(f_{1}+f_{2}\left | \rho v_{x} \right |) \right ]\right \}=0 \ \ \ \ (Eq.3a)$

$\left [ \frac{\delta v_{y}}{\delta {x}}-\frac{\delta v_{x}}{\delta {y}} \right ] - \left \{ v_{x} \left [ \frac{\delta}{\delta {y}}(ln(f_{1}+f_{2}\left | \rho v_{y} \right |) \right ] -v_{y} \left [ \frac{\delta}{\delta {x}}(ln(f_{1}+f_{2}\left | \rho v_{y} \right |) \right ]\right \}=0 \ \ \ \ (Eq.3b)$

I tried defining the above two equations in many ways, but ends with no success. The pressure on the other hand is solved comfortably with no errors.
Equs. (3a and b) is defined in OpenFOAM as,

Quote:

(gradCurlUyx - gradCurlUxy) = (1/0.4343*(f1+(f2*rho*Ux)))*((Ux*gradUxy)-(Uy*gradUxx)); // (Eq.3a)
(gradCurlUyx - gradCurlUxy) = (1/0.4343*(f1+(f2*rho*Uy)))*((Ux*gradUyy)-(Uy*gradUyx)); // (Eq.3b)
//COMPILED WELL - but no change in velocity during post-processing (Attachments)

Previously, I got the comment from one of the foamers that I didn't defined the assignment operator appropriately. It looks to be trivial problem, but I couldn't figured it out so far.

Quote:

solve
(
(gradCurlUyx - gradCurlUxy) == (((Ux*gradUyy)-(Uy*gradUyx))/(0.4343*(f1+(f2*rho*Ux))))
); // Failed when I try to define the velocity equation based on equality operator
ERROR:
ergunFoam.C: In function ‘int main(int, char**)’:
ergunFoam.C:62:88: error: no match for ‘operator==’ in ‘Foam:

perator-(const Foam::GeometricField<TypeR, PatchField, GeoMesh>&, const Foam::GeometricField<Type1, PatchField, GeoMesh>&) [with Type1 = double; Type2 = double; PatchField = Foam::fvPatchField; GeoMesh = Foam::volMesh; typename

I'm hereby attaching my code and case files.
If anyone have some ideas, kindly do share it to proceed further.
Thank you

**The above equations are referred from the following reference: Equ. (9) expanded as 2 Equs. [Equ. 21 - cylindrical coordinates]
https://aiche.onlinelibrary.wiley.co.../aic.690200519