# High-speed gas flow

Hello,

I'm just getting familiar with DSPH and would like to ask for some direction on how to simulate high pressure and high speed gas flow. I have adjusted the viscosity, density parameters under the <constantsdef> section but not sure how to represent high pressure expanding gas.

My problem is quite simple; I am looking to find out the pressure variation in air due to a sphere of high pressure gas expanding quickly over a flat surface. I have it done in OpenFOAM and would like to compare the findings with DSPH.

(as in high pressure: several Mach....so in essence an exploding bubble of air)

Any help is appreciated

Thanks

Andy

## Comments

hi @TheMadHungarian

im looking for these issues too... @circles and @JOJO stated in another post they added background pressure to two-phase code, im not sure if only this would make it work, but definitly needs to be added. im insecure about making changes in the code so im waiting for them if they can show exactly how they added the term. if you get any news on this, please share it here.

thankss

Look at MOKOS, A., ROGERS, B. D. & STANSBY, P. K. 2016. A multi-phase particle shifting algorithm for SPH simulations of violent hydrodynamics with a large number of particles. Journal of Hydraulic Research, 1-20. DOI: 10.1080/00221686.2016.1212944

"A pressure difference is created between the volume and the surrounding area, forcing the air volume to gradually expand. The aim of this case is to demonstrate the effect of the shifting algorithm on the anisotropic particle spacing and test the applicability of the free surface correction to the air phase. "