We recently proved that a dissipative residual-based scheme of second-order accuracy is vorticity-preserving for the compressible Enter equations. In the present paper, this scheme is extended to curvilinear grids and...
详细信息
We recently proved that a dissipative residual-based scheme of second-order accuracy is vorticity-preserving for the compressible Enter equations. In the present paper, this scheme is extended to curvilinear grids and applied to the computation of the interaction between a Scully vortex and a NACA0012 airfoil at a Mach number of 0.5. A grid convergence study and a comparison with a conventional scheme and with experimental measurements are presented. The new scheme shows a faster grid convergence, especially for the vortex trajectories and deformations during the interaction.
Two-dimensional detonation simulations are carried out in cavity-based channels to investigate detonation wave interaction with cavity in supersonic combustible mixtures. When the detonation wave crosses over the cavi...
详细信息
Two-dimensional detonation simulations are carried out in cavity-based channels to investigate detonation wave interaction with cavity in supersonic combustible mixtures. When the detonation wave crosses over the cavity during backward propagation, an oblique shock wave is first originated from the left edge of the cavity, resulting in the formation of detonation bifurcation associated with an unburned jet. Rather than failure and disappearance, the detonation wave realizes relatively dynamic sustainment during backward propagation. Large-scale vortices along the highly unstable shear layers due to the Kelvin–Helmholtz instability enhance the mixing effect, accelerate the consumption of the unburned jet, and further the subsequent chemical heat release, which plays a significant role in detonation sustainment. A periodical process of forward propagation, detonation attenuation, and detonation sustainment is formed due to detonation wave interaction with cavity, thus being able to avoid detonation failure in cavity-based channels when the incoming velocity is higher than the Chapman–Jouguet velocity.
In the present work, detonation stabilization in the supersonic flow is numerically investigated in the straight channel with suction boundaries. The two-dimensional reactive Navier-Stokes equations, together with a o...
详细信息
In the present work, detonation stabilization in the supersonic flow is numerically investigated in the straight channel with suction boundaries. The two-dimensional reactive Navier-Stokes equations, together with a one-step reaction model, are solved using a second-order-accurate finite volume method solver based on the structured adaptive mesh refinement framework. The results show that, compared with one jet initiation, detonation initiation can be achieved in a shorter distance using two hot jets subject to the equal total width of the jets. When the suction slots are turned on, the overdriven detonation undergoes a gradual attenuation along with the weakening of the transverse waves, hence leading to dynamic detonation stabilization in the supersonic flow. When the suction slots are closer to the detonation front, the forward propagation of the detonation in the supersonic flow can be more effectively prohibited, implying that the suction slots should be distributed as close as possible to the detonation front in order to realize the maximal suction effect using the minimal suction slots.
Dielectric barrier discharge actuators are promising candidates for supersonic boundary-layer transition control because of their ability to concentrate energy transfer in receptive regions in the depth of the boundar...
详细信息
Dielectric barrier discharge actuators are promising candidates for supersonic boundary-layer transition control because of their ability to concentrate energy transfer in receptive regions in the depth of the boundary layer. A detailed understanding of the plasma-flow coupling mechanisms and optimum scaling in compressible flows is necessary to develop efficient actuation schemes. In this work, the dielectric barrier discharge momentum transfer to an unstable laminar boundary layer over a flat plate under different Reynolds and freestream Mach numbers is studied. A new coupled plasma-compressible flow solver using a block-structured adaptive mesh refinement algorithm is presented, which was developed to model the force field generated by the actuator. The spectral components of the force are used as source terms for the study of the influence of flow conditions and length scales on linear receptivity.
Multigrid methods are well suited to large massively parallel computer architectures because they are mathematically optimal and display good parallelization properties. Since current architecture trends are favoring ...
详细信息
Multigrid methods are well suited to large massively parallel computer architectures because they are mathematically optimal and display good parallelization properties. Since current architecture trends are favoring regular compute patterns to achieve high performance, the ability to express structure has become much more important. The hypre software library provides high-performance multigrid preconditioners and solvers through conceptual interfaces, including a semistructured interface that describes matrices primarily in terms of stencils and logically structured grids. This paper presents a new semistructured algebraic multigrid (SSAMG) method built on this interface. The numerical convergence and performance of a CPU implementation of this method are evaluated for a set of semistructured problems. SSAMG achieves significantly better setup times than hypre's unstructured AMG solvers and comparable convergence. In addition, the new method is capable of solving more complex problems than hypre's structured solvers.
This paper presents results of a multiphase computational fluid dynamics code using a coupled level-set/volume-of-fluid method to simulate liquid atomization. This interface-capturing approach combines the mass conser...
详细信息
This paper presents results of a multiphase computational fluid dynamics code using a coupled level-set/volume-of-fluid method to simulate liquid atomization. This interface-capturing approach combines the mass conservation properties of the volume-of-fluid method with the accurate surface reconstruction properties of the level-set method, and it includes surface tension as a volume force calculated with second-order accuracy. Developed by one of the authors, the multiphase code builds upon the combined level-set/volume-of-fluid methodology to enable bubbly flow, liquid breakup, and phase-change simulations. The extension presented in this paper couples a Lagrangian dispersed phase model for postbreakup tracking of droplets with block-structured adaptive mesh refinement on the Eulerian grid. Under an appropriate set of criteria, the transfer of droplets representation from the Eulerian to the Lagrangian discretization enables the simulation of sprays on larger domains and for longer physical times without degrading the overall accuracy of the calculation. A demonstration for like-on-like jet impingement of relevance to cold startup of liquid rocket engines is presented here at low, moderate, and high injection velocities, including validation with experimental data.
暂无评论