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- - **Problem with pseudo shock simulation!**
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Problem with pseudo shock simulation!Hi Guys!! am doing simulation on constant area straight ducts which mimics supersonic inlet isolators, i would like the study the pseudo shock phenomenon that occurs due to shock wave boundary layer interactions.
My problem domain is a cuboid with dimension 80x80x960 all in mm.. owing to computation i reduced the cross section dimension to 40x40 mm, with two long faces of cuboid set to symmetry. n length remained same. Grid : cuboid with above dimensions; structured grid with grid fined near the corner region, 1.5 million hexahedral cells, cell squish is around 0.2 Solver settings: Density based, implicit, absolute velocity formulation. Material, Air as ideal gas, viscosity :sutherlands formulation. Turbulence model: standard K - omega model with low re number effect & shear flow corrections enabled, Boundary conditions are as follows, Pressure inlet : momentum- tot pressure 196000pa supersonic int gauge pressure - 25050 pa Turbulence parameters Hydraulic diameter 0.08m intensity 5 % Total Temperature : 300k pressure outlet : momentum-gauge pressure - 25050 pa Turbulence parameters Hydraulic diameter 0.08m intensity 5 % Total temperature : 300k wall : no slip & stationary, heat flux set to zero (adiabatic!) symmetry : default symmetry Solver is a STEADY SOLVER ( just to obtain initial conditions for UNSTEADY SOLVER) discretization: flux : AUSM flow : third order MUSCL Turbulence scalar equations : QUICK CFL set to default value of 5. wall y+, i calculated using NASA viscous grid spacing calculator i fixed y+ of 30 which throws cell height of 1e-5m!! Re.no is 3.8*e6 with reference length as hydraulic diameter.. The problem is my solution is not converging beyond 1e-5, residuals fluctuate around 1e-5.. i set the convergence criteria to 1e-6.!! Is it enough to switch to unsteady solver??? If that the case what value of time step i provide?? also max iterations per time step..I'm stuck with this, Help me.. Also when check with the contour, fluent shows the max wall y+ value of 19 near the wall though i set the cell height for y+ 30. Thanks in advance. |

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