FreeCASE - Free(dom) Computational AeroServoElasticity
Last update:
January 15. 2016 14:05:15

Incompressible limit

In this section we present the numerical results of AeroFoam solver for a 2D aerodynamic test problem, such as the inviscid unsteady flow around a fixed cylinder in the incompressible regime, since characteristic splitting methods suffer a little when the freestream Mach Moo number is very low.

Problem definition

  • Domain:
    • Internal circular subdomain with radius R = 0.5 m
    • External circular subdomain with radius Roo = 25 m >> R
  • Material:
    • Polytropic Ideal Gas (PIG)
    • Specific heat ratio gamma = 1.4
    • Gas thermodynamic constant R = 287.05 J/kgK
  • Initial conditions: 
    • Thermodynamic pressure Poo = 101325 Pa
    • Temperature Too = 288.15 K
    • Mach number Moo = 0.1
  • Boundary conditions:
    • Slip boundary conditions on internal subdomain
    • Riemann boundary conditions on external subdomain


Figure: Problem definition.

Space and time discretization

  • Space discretization:
    • Mesh created with Gmsh
    • # of triangular cells Nv = 15247
    • # of nodes Nn = 15484
  • Time discretization:
    • Total simulation time endTime = 0.2 s
    • Timestep deltaT = 1e-5 s
    • Maximum Courant number maxCo =  1.5


Figure:
Computational grid.

Numerical results

  • Comparison with exact solution of potential theory
  • Single iteration CPUtime = 0.09 s on AMD64 3500+ desktop PC with AMD Athlon 64 2.2 GHz CPU, 1 Gbyte RAM, 512 Kbyte L2 cache


Figure:
Pressure coefficient Cp distribution.

Download

  • IncompressibleLimit.tar.gz test problem folder. Uncompress this archive in the OpenFOAM work folder and execute AeroFoam . Cylinder_15k_M010 from terminal to start the simulation. Download.



Powered by cmsimple.dk