Two-Fluid Effective-Field Equations
Mathematical Issues Non-conservative: –Uniqueness of Discontinuous solution? –Pressure oscillations Non-hyperbolic system: Ill-posedness? –Stability –Uniqueness How to sort it out?
Remedy for hyperbolicity: Interfacial pressure correction term and virtual mass term
Modeling – Interfacial Pressure (IP) Stuhmiller (1977):
Here, we have
Faucet Problem: Ransom (1992) Hyperbolicity insures non-increase of overshoot, but suffering from smearing Location and strength of void discontinuity is converged, not affected by non- conservative form Effect of hyperbolicity Solution convergence
Modeling – Virtual Mass (VM) Drew et al (1979)
VM is necessary if IP is not present, the coefficients are unreasonably high for droplet flows. Requirement of VM can be reduced with IP.
Numerical Method Extended from single-phase AUSM + -up (2003). Implemented in the All Regime Multiphase Simulator (ARMS). -Cartesian. -Structured adaptive mesh refinement. -Parallelization.
A case with 40% liquid fraction U gas =1km/s L =0.4, liquid mass =400kg V L =150m/s(in radial) Liquid area: l=2m, r=0.4m L=60m R=12m Axis ( Grid size 10cm, calculation time :0-150ms Calculation domain:,L=60m,R=12m )
Liquid fraction, pressure and velocity contours of particle cloud for time ms. Lquid fraction (Min: Max:10 -3 ) Pressure (Min:1bar-Max:7bar) Gas Velocity (Min:0m/s -Max:1,000m/s)
Droplet radius R = 3.2mm, incoming shock speed M = 1.509
Current and future works Complete the hyperbolicity work on the multi-fluid system. Complete the adaptive mesh refinement into our solver – ARMS Expand Music-ARMS to solve 3D problems. Introduce physical models: Surface tension model Turbulence model Verification and validation. Real world applications.