Exhaust Manifold simulation

rohith0698 · May 31, 2021, 12:32

I am given an exhaust manifold CAD. The task is about analysing the pressure drop and the thermal behaviour of the manifold.
Inputs 1) Mass flow rates of the inlet along with the static temperatures at the inlet runners
2) Outlet pressure value and the temperature at the outlet along with a convection medium heat transfer coefficient and ambient temperature.
Question
1) Do I need to change the initial conditions(I mean the static temperature) of the 2 continuums (solid and the fluid) or should I give the inlet temperature at the regions.
2) I have used a surface remember, tetrahedral mesh and a prism layer mesh. Is it okay ?
3) I have selected a 3-dimensional, gaseous steady state, turbulent coupled flow and a constant density model for the fluid and a 3 dimensional steady state solid with coupled solid energy and constant density for the solid continuum.
My values aren’t converging…. Where am I going wrong ?
Thanks in advance.

DrDerpy13 · June 5, 2021, 18:25

there is a tutorial in user guide which has a similar case to yours and it is explained step by step how to do both fluid flow and heat transfer. I think you can find it in the heat analysis section

ashokac7 · June 6, 2021, 13:27

Some quick tips-
1. Go with polyhedral meshed for Fluid and Thin meshed for the solid
2. Try to maintain conformal contacts.
3. No need for coupled flow here, go with segregated flow first.
4. Model density using Sutherland's law (take ideal gas)
5. Initial conditions are just for initial guess. So to avoid divergence issues, we try to take initial conditions close to our boundary conditions
6. Apply mass flow in, temperature for BCs.
7. Hope you are using natural convection HTC at outer solid surfaces.

May 31, 2021, 12:32	Exhaust Manifold simulation	#1
rohith0698 New Member Rohith Prakash Join Date: May 2021 Posts: 1 Rep Power: 0	I am given an exhaust manifold CAD. The task is about analysing the pressure drop and the thermal behaviour of the manifold. Inputs 1) Mass flow rates of the inlet along with the static temperatures at the inlet runners 2) Outlet pressure value and the temperature at the outlet along with a convection medium heat transfer coefficient and ambient temperature. Question 1) Do I need to change the initial conditions(I mean the static temperature) of the 2 continuums (solid and the fluid) or should I give the inlet temperature at the regions. 2) I have used a surface remember, tetrahedral mesh and a prism layer mesh. Is it okay ? 3) I have selected a 3-dimensional, gaseous steady state, turbulent coupled flow and a constant density model for the fluid and a 3 dimensional steady state solid with coupled solid energy and constant density for the solid continuum. My values aren’t converging…. Where am I going wrong ? Thanks in advance.

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June 5, 2021, 18:25		#2
DrDerpy13 New Member Vlad Join Date: Oct 2020 Posts: 13 Rep Power: 6	there is a tutorial in user guide which has a similar case to yours and it is explained step by step how to do both fluid flow and heat transfer. I think you can find it in the heat analysis section

June 6, 2021, 13:27		#3
ashokac7 Senior Member Ashok Chaudhari Join Date: Aug 2016 Location: Pune, India Posts: 260 Rep Power: 11	Some quick tips- 1. Go with polyhedral meshed for Fluid and Thin meshed for the solid 2. Try to maintain conformal contacts. 3. No need for coupled flow here, go with segregated flow first. 4. Model density using Sutherland's law (take ideal gas) 5. Initial conditions are just for initial guess. So to avoid divergence issues, we try to take initial conditions close to our boundary conditions 6. Apply mass flow in, temperature for BCs. 7. Hope you are using natural convection HTC at outer solid surfaces.