Engine Simulation: Help with Physics Models

Anolen · July 30, 2018, 19:28

Hey everyone,

I am working on a simple simulation for a final project, and am a bit stumped with setting up my simulation.

I am comparing the average density in two cylinders, one with a single intake valve, and one with two (to compare a 2-valve vs. 4-valve cylinder head). I am trying to make it as simple as possible, so there are no moving components etc. Nonetheless, I am rather stumped while trying to figure out an effective setup for my physics model. In terms of regions, there is only an inlet and walls, as I only want to measure density after a certain amount of time. It is a grossly simple simulation/ comparison, but will work for the project if I can get it to run properly. I have tried a stagnation inlet and a velocity inlet over a period of time and I am running into continuous problems. Residuals are all over the place and very high, and I have yet to see a density that looks reasonable.

Currently I am using the following physics models: 3-D, steady, coupled, ideal gas, k-omega turbulence and cell quality remediation.

I've attached a picture of the model I am using, if I am leaving out important info let me know, I'm just not sure where to look or what to change at this point so any advice would be appreciated.

Thanks everyone.

shelleyvander · July 31, 2018, 05:02

i have a 6500 for 6 years now i got at harbor and its still a beast i hook it directly to my panel i have a permenate connection on both rails i just turn off the main so it doesnt back feed and kill a line man and flip 2 breakers i installed on the bottom of the panel plug this 220 line into the diesel generator and give it a pull mine is hooked to my 500 gallon propane tank so if the power goes out its flip 3 breakers and 1 pull i live in tornado alley we lose power alot and its awesome

AndreP · July 31, 2018, 09:20

I never did Engine Simulations, only external vehicle flow, but are you sure that the K-Omega is the adequate Turbulence model for internal combustion?

While I was searching for the turbulence model to use in my project I came across some references that would indicate that K-Epsilon and K-Omega SST is good for external flow, but for Internal Combustion you would need a more robust (and heavier) turbulence.

I'm not saying it needs to be another one, but maybe you would like to do a search and find if that turbulence model will actually give you reasonable results in your problem type? Because the turbulence model is actually one of the most important settings in a CFD simulation!

Also, what mesh are you using? in the inlet and outlet, you can use Trimmer as the flow should be pretty linear, but inside the combustion chamber i think you should use Polyhedral as its a highly turbulent environment!

Also, your image is all black, so we can't really have a look what you shared or what does it look like your problem!

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July 31, 2018, 05:02		#2
shelleyvander New Member shelleyvander Join Date: Nov 2017 Posts: 5 Rep Power: 9	i have a 6500 for 6 years now i got at harbor and its still a beast i hook it directly to my panel i have a permenate connection on both rails i just turn off the main so it doesnt back feed and kill a line man and flip 2 breakers i installed on the bottom of the panel plug this 220 line into the diesel generator and give it a pull mine is hooked to my 500 gallon propane tank so if the power goes out its flip 3 breakers and 1 pull i live in tornado alley we lose power alot and its awesome

July 31, 2018, 09:20		#3
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	I never did Engine Simulations, only external vehicle flow, but are you sure that the K-Omega is the adequate Turbulence model for internal combustion? While I was searching for the turbulence model to use in my project I came across some references that would indicate that K-Epsilon and K-Omega SST is good for external flow, but for Internal Combustion you would need a more robust (and heavier) turbulence. I'm not saying it needs to be another one, but maybe you would like to do a search and find if that turbulence model will actually give you reasonable results in your problem type? Because the turbulence model is actually one of the most important settings in a CFD simulation! Also, what mesh are you using? in the inlet and outlet, you can use Trimmer as the flow should be pretty linear, but inside the combustion chamber i think you should use Polyhedral as its a highly turbulent environment! Also, your image is all black, so we can't really have a look what you shared or what does it look like your problem!