Gaseous detonation propagation through a bifurcated tube was numerically investigated. A 2^nd additive semi-implicit Runge-Kutta method and a 5^th order WENO scheme were used to solve two-dimensional reactive Euler equations. A detailed chemical reaction model was utilized to describe the heat release of detonation. The contours of density, pressure, temperature, species OH mass fraction, the computed cellular pattern and the traveling speed of detonation were obtained. The results show that, influenced by the rarefaction waves from the left sharp comer, the reaction zone is separated from the leading shock. Then, the detonation is degenerated into the deflagration. The winkled reaction front can be clearly identified in numerical schlieren and temperature contours. Re-initiation is induced by the leading shock reflection on the right wall in the vertical branch. Mach reflection of disturbed detonation occurs in both vertical and horizontal branches. The boundary between regions of uniform and larger cells is not a straight line; it doesn't exactly start at the left sharp comer and is usually upstream of the left sharp comer. The triple-point trajectory characterizing Mach reflection locates downstream of the right comer in the horizontal branch. Complex structures of vortices, the unreacted region, and shock-vortex interaction are observed in flow field around the left comer. Vortices accelerate reaction rates of the unreacted region. The reflected shock interacts with vortices and breaks them into pieces. Reflected shock also accelerates the consumption of the unreacted region and then an embedded jet is produced. The evolution of detonation wave and computed cellular pattern are qualitatively consistent with those from experiments.

The numerical simulations is carried out on interface with large deformation induced by interaction between a moving shock and Helium bubbles.The high performance of the level set method coupling with GFM (ghost fluid method) method was demonstrated. Upwind TVD scheme was used to solve Eulerian equation for flowfield,and 5th WENO scheme was used to solve level set equation for fluid interfaces' tracking.GFM was applied to deal with the interface boundary.Example in Ref.[1] was used to validate our codes.Finally,the results were obtained on moving shock interacting with helium bubbles including the bubbles evolution.The results indicate that multi-interface can be perfectly tracked by extension of level set equation for multi-fluid interfaces.

Upwind TVD scheme is used to solve laminar, 2D fully N-S equations.A shock diffracted by a cylinder or square cylinder along hydrogen air interface, and mixing enhancement in a shear flow are numerically studied.The results indicate that the shock travels faster in hydrogen.An adjustable shock and a swirling ovrtex appear in the shear region.After the swirling vortex impacts the cylinders, a reflected shock is formed, and hydrogen diffuses downstream in the region near cylinder walls.Contact surfaces are deformed and another vortex is generated.The distribution of hydrogen shows that the mixing is enhanced effectively by inserting cylinders along the interface, expecially for a square cylinder.The transition from RR to MR can be found for shocks traveling both in air and in hydrogen for a cylinder.Two Mach stems will transmit each other at the downstream.But in the case of a square column, the shock is almost not affected along the lower wall but Mach reflection takes place along the upper wall, then a diffracted shock and a Mach stem transmit each other finally.For both cases, the detached shock occurs on the right of cylinders.Similar shock structures arise, and contributions of cylinder shape are eventually forgotten.