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-   -   Model and Boundary Conditions for Flow around a Bullet in Ansys Fluent (https://www.cfd-online.com/Forums/fluent/184496-model-boundary-conditions-flow-around-bullet-ansys-fluent.html)

chaithanya1996 March 3, 2017 18:33

Model and Boundary Conditions for Flow around a Bullet in Ansys Fluent
 
Hello Everyone

I am working on a project to study the Flow around Long Range Bullets particularly Remington Fireball. I thought of simulating the flow in Ansys Fluent but I have no idea which boundary conditions and which model will give a realistic estimate of Drag on the bullet in such supersonic conditions Any ideas and References would be Deeply appreciated

Thank you

jabier14 March 3, 2017 18:48

Perhaps this may give you a good starting point:

https://confluence.cornell.edu/displ...+Specification

I imagine your problem will be a somewhat similar setup.

chaithanya1996 March 3, 2017 18:59

Quote:

Originally Posted by jabier14 (Post 639377)
Perhaps this may give you a good starting point:

https://confluence.cornell.edu/displ...+Specification

I imagine your problem will be a somewhat similar setup.

Thanks for the reply Here we are talking about the mach regimes oh 3-3.5 as the the velocity of remmington fireball bullet will be at speeds of 1200m/s and that seems to result in bubble shock waves as like below

https://www.youtube.com/watch?v=gnhbhpwTx1c

so the above analysis comes short i guess

LuckyTran March 5, 2017 22:45

Quote:

Originally Posted by chaithanya1996 (Post 639378)
Thanks for the reply Here we are talking about the mach regimes oh 3-3.5 as the the velocity of remmington fireball bullet will be at speeds of 1200m/s and that seems to result in bubble shock waves as like below

https://www.youtube.com/watch?v=gnhbhpwTx1c

so the above analysis comes short i guess

Replace the wedge with your bullet. Change the inlet properties to achieve your desired wind speed. It is straightforward. How does it come short of your expectations? What exactly do you want to do that is not answered?

The skin friction does not contribute much to the drag compared to across the shockwaves, so it really doesn't matter if you use a turbulence model.

There's two ways you can setup the problem. With the bullet stationary and some sort of supersonic inlet, or you can explicitly specify a velocity for the bullet and use a simple pressure inlet (with pressure equal to atmospheric pressure). I recommend the later.


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