[GV77]

Hi:
My simulation consists in an interaction between two jets (one with diameter = 1 mm and the other with diameter = 16 mm) and a crossflow (bigger inlet on the left). The crossflow consists of a mixture of combustion products (temperature = 1360 K), the small jet is H2 and the big jet is atmospheric air (both with temperature = 298 K). My model is 3D, and the figures depict fluid flow direction in the midsection of the domain. I’m using the steady flow model, with segregated solver and ideal gas model. The turbulence is modelled with k w SST model. The pressure outlet is 0 Pa.

I turned on gravity in a simulation and turned off it in another simulation. The direction of gravity is drawn in the figures with a blue arrow. The simulation with gravity has backflow in the outlet and that makes the simulation less efficient. I know that sometimes gravity model creates this problem because of the definition of the reference altitude (I set this value with the coordinates of the crossflow axis in the outlet) and/or density (value of the lightest gas, which is H2) values. I read an article in Steve’s Portal (https://community.sw.siemens.com/s/a...olved-with-VOF) in which the author recommends setting the fluid density to the lightest fluid in the domain and I followed that advice (I’m not using VOF, I’m only studying one phase – gas phase).

My suggestion to solve this problem would be reduce the downstream length to avoid that behaviour because now I know where the recirculation begins (yellow blur). Does anyone suggest a different approach to solve this problem? Or could someone suggest some documentation or post?