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Re-entry satellite - High Mach Number
Posted Jun 21, 2018, 8:44 p.m. EDT Computational Fluid Dynamics (CFD), Heat Transfer Version 5.2a 0 Replies
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Hello,
I study the aerothermal effects of a CubeSat which comes back to earth. At the end, I have to find the temperature of the satellite. First, I made lot of research, and I seen that the satellite has an order magnitude of velocity and mach number respectively of 6720m/s and 24 at physical properties of the atmosphere at 80 km altitud. But first I simplify a bit that by imposing atmosphere condition at 0m altitude, velocity at 2940 m/s and mach number at 2.4.
That's why, I try to work with High Mach Number Flow (hmnf) but I have some problems. I use Spalart-Allmaras option that I think the best for my topic. Concerning BC's, I define just an inlet for the velocity, outlet for environment and wall for satellite. I don't take care to heat transfer yet. Then I refine the mesh as extremely fine near to the satellite with boundary layers.
Finally, my simulation doesn't work and I don't understand why. I have this error message :
Failed to find a solution. Segregated Step 1 Attempt to evaluate nonintegral power of negative number. Function: ^ Failed to evaluate variable. Variable: comp1.hmnf.mu, Defined as: ((comp1.hmnf.Tmu ref+comp1.hmnf.S s)(((comp1.T/comp1.hmnf.Tmu ref)^1.5)comp1.hmnf.mu ref))/(comp1.hmnf.S s+comp1.T) Failed to evaluate variable. Variable: comp1.hmnf.time step inv, Defined as: max(sqrt(((2^gmg level)^2)emetric(comp1.u,comp1.w)),comp1.hmnf.mu/(((comp1.hmnf.lref0.5)^2)comp1.hmnf.rho)) Failed to evaluate expression. Expression: nojac(comp1.hmnf.time step inv/comp1.hmnf.locCFL) Failed to evaluate expression. Expression: dvol(r(pi((nojac(comp1.hmnf.time step inv/comp1.hmnf.locCFL)(2comp1.hmnf.rho))(-(comp1.w-nojac(comp1.w)))))) Failed to evaluate Jacobian of expression. Expression: (2comp1.hmnf.rhonojac(comp1.hmnf.time step inv/comp1.hmnf.locCFL)(-(comp1.u-nojac(comp1.u))test(comp1.u)-(comp1.w-nojac(comp1.w))test(comp1.w))pir)*(dvol) In Segregated Step 1: There was an error message from the linear solver. The relative error (0.002) is greater than the relative tolerance. Returned solution is not converged.
I searched in COMSOL help but I haven't found any solutions.
Please can you help me ? If you have any tips or assumptions ... I share you my simulation to check it if you have time.
Thank you by advance.
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Hello Olivier Lambert
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