[ChiefSeaBiscuit]

Hello all,
I'm messing around with CHT modelling in Converge and I've hit a snag. I've fully read the theory behind it and was able to conduct a simulation of heat transfer of airflow hitting a ball so I understand the settings. However, i'm messing around with a heat exchanger within a hot fluid flow and is being cooled down by a coolant gas. The outside of the heat exchanger is shown in the pictures as greeny colour, the inside is also shown in red and the inflow/outflows of the pipes are shown as different colours connected to the red. The whole heat exchanger is inside a box with simple inflow/outflow and slip condition walls (not shown).

The issue is the simulation won't run due to "the surface has a non-interface triangle that is only connected to a single interface triangle" to try and rectify this I tried changing the pipe next to the inflow to a WALL instead of INTERFACE as this would be connected to more than one triangle? (The wall is in purple) Yet the same error comes up, does anyone know of any solution? Or a way to have an inflow so that I can model cooling down a system using a coolant?

Thanks in advance.

Therm1.png

Therm2.jpg

Therm3.png

Therm4.png

[SauravMitra]

Hi Adrian,

Refer to the setup in our tutorial case uploaded in our website. Find the file pipe_flow_cht_with_udf.tar.gz to download.
You will see we are dealing with a pipe flow with an Inlet and an outlet. We have a solid-fluid interface in the setup. Follow the region, stream id and the boundary id definitions.

It seems you have multiple interface boundaries. Make all of them WALLS, and then turn each one of those into INTERFACE one by one preserving the setup consistency. Sooner or later, your setup will be free from errors.
The first CHT setup in CONVERGE takes some time but you will get used to it soon.

Best,

[ChiefSeaBiscuit]

Apologies for the late reply, I've been tinkering with the CHT modelling.

I am still having problems with this simulation, I've narrowed the problem down however to the "coolant" which has a interface connected directly to inlets/outlets with it giving the same error msg. The red (interface) and yellow (in/outflow) indicate this in this case. I've also looked at the template CHT model that you have and set my boundaries to be almost identical but to no avail. Is there another solution for this?

Side note: I've run a CHT simulation before with a metal block inside a fluid path to get to grips with the settings and such so I understand the settings and setup but just having trouble when there is an inflow as well. I also noticed that there is a non manifold issue with the CHT template? Is this on purpose to solve this problem??

Many thanks,
Adrian

[SauravMitra]

Hi Adrian,

You are close. And I am sure you will be able to nail the rest.

See if you are maintaining any of these rules:

a) An Interface boundary has connections to 2 wall boundaries or 2 inflow/outflow boundaries.

Or

b) An interface boundary has connections to one wall and another inflow/outflow boundary.
Refer to the tutorial CHT case now. You will see that the interface boundary has connections to fluid inflow boundary and solid wall on one side. On the other side, interface boundary has connections to fluid outflow boundary and solid wall.
Or

c) If an interface boundary is only connected to another Interface boundary.

The problem that you are facing is most probably because, you are connecting an Interface boundary to a single wall boundary or a single inflow/outflow boundary. This is not allowed, because an interface boundary is a double-sided triangle. It needs to see the two sides via the connections. That is what the error message is saying.

Finally, use the latest Studio version from our downloads website. If you have setup the Interface boundary correctly, you should not see "Nonmanifold problems". But if you change the same triangles to Wall boundary, then it would become a case of Nonmanifold problem. Again, the explanation of this is as before, an Interface boundary is a double-sided triangle and there is a clear determination of the inner direction of normals and outer direction of normals. While any non-interface boundary have one-sided triangles. Refer to Chapter 3 in Theory Manual regarding the discussion of Nonmanifold problems.

Best,
Sauravl