Facing a problem in my college’s openFOAM project as a beginner, can ya'll help me out…😭🤧
Hi. I'm working on a stratified domain with a temperature difference of 20K while using buoyantBourssinesqPimpleFoam solver and LES WALE model on openFOAM v2412.
My domain configuration is 5 X 1 X 1m. My Flow is along +ve X direction with Z being the vertical direction along height. There are 2 hills inside my domain, both being 1.5m and 2.5m away from inlet.
Internal field is linearly stratified from bottom to top using python file (T=290+20*z; as z varies from 0 to 1m, the value of temp changes). Inlet has continuous stratified flow entering with 0.0767m/s to satisfy Froude No.=0.5.
I got significant negative Ux at the outlet almost immediately. At around 0.2-0.6s, I see spatially organized bands at the outlet and sometimes flow apparently entering the domain through the outlet.
What's confusing is that the hill is nowhere near the outlet at this point. At 0.0767 m/s (inlet velocity) the 5 m advective travel time is ~65 s. At 1 m/s, however, the outlet behaviour looks much more reasonable. This makes me suspect either a low-Froude/stratification effect or a numerical/BC issue.
I'm providing some pictures and boundary conditions hoping someone helps me get out of this mess. I've tried changing BCs but it didn't work out at all. My doubt is on outlet boundary conditions causing initial Pressure-Velocity coupling misconfiguration and major backflow throughout the 100 seconds, as evident from Ux field...