[mbranag]

I created a geometry which consists of a pipe that has cool water flowing through it. On the outside of the pipe is a region of hot oil that is flowing across the pipe.

Initially the geometry was created in a rectangular domain. The initial points were created in the xy plane. A second set of points were created by using the same xy coordinates but with a new z-coordinate. I was getting solutions that seemed reasonable and was getting a temperature drop in the oil as it flowed over the pipes.

Next I applied a curve to the geometry. So instead of simply extruding the geometry from the xy plane, I rotated the points about an axis (parallel to the y-axis). I also added curved edges between the points on the xy plane to this new rotated plane.

Now, the solution is failing to solve and I am getting a negative initial temperature error in the Hot Oil region. Looking at the output, the max/min temperatures in this region don't seem to change much based on the calculations until the end when the minimum swings changes drastically into the negative.

I have tried increasing the mesh in the direction of the rotation and in the regions with larger volumes. I have run checkMesh and all the results are reported as "OK". I have changed my surface normal schemes in all regions to account for the decreased orthogonality of the mesh (max of 41 degrees). The only change I made to the boundary condition was to correct the velocity boundary condition (inletOutlet) of the Cool Water which flows out the newly rotated plane. I have also tried tweaking the time steps of the solution and have not seen much variation.

[peterhess]

Hello!

I made many changes that I do not even remember

At least the negative temperature is now solved.

See case update_1

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The Boundaries in hotOil:

AxialEnd1

and

AxialEnd2

are defined to be patch.

Is that right or they need to be wall?

As you defined, the fluid is leaving the regin hotOil through three outlets!

I changed those to wall.

Like that the fluid is leaving just through one outlet...

See case update_2

I did not check the results...

Regards

Peter

[mbranag]

Thanks so much! That really helped! I was actually leaving the axial ends open as I am modelling a segment of a circular coiled cooler. I might try changing the axial ends of the hot oil to by a symmetry planes.

Thanks!