In the present work, the optimization of the abrasive water jet machining (AWJM) process parameters with multiple performance characteristics based on the orthogonal array with the grey relational analysis (GRA) has been studied. Optimization of multiple response characteristics is far more complex compared to optimization of single performance characteristic. A grey relational grade (GRG) calc...

We propose a flux vector splitting (FVS) for the solution of film flows radially spreading on a flat surface created by an impinging jet using the shallow-water approximation. The governing equations along with the boundary conditions are transformed from the physical to the computational domain and solved in a rectangular grid. A first-order upwind finite difference scheme is used at the point...

The circular hydraulic jump exhibits behavior quite different from that commonly observed in planar jumps. Here we examine experimentally some of the causes and consequences of those differences. We suggest that surface tension plays a dominant role in establishing the shape of the circular jump for impinging jets. The importance of surface tension is a direct result of the thinness of the liqu...

Liquid films flowing over rough substrates are influenced by asperities whose sizes are comparable to the film thickness. We investigate flows driven by jet impact on a regular array of micron-size posts. We show that the topography modifies the size and the shape of the observed hydraulic jumps: in addition to circular jumps, we obtain a variety of stable polygonal shapes. We rationalize our r...

This paper reports oneand two-dimensional simulations of cavitating flows by the Space-Time Conservation Element and Solution Element (CE/SE) method. A continuum cavitation model based on specifying the speed of sound of two-phase flows is employed. The CE/SE method is a viable CFD method for flows at wide range of Mach numbers. The method is explicit and is suitable for time accurate simulatio...

We present the results of an experimental investigation of the striking flow structures that may arise when a vertical jet of fluid impinges on a thin fluid layer overlying a horizontal boundary. Ellegaard et al. (1998, 1999) demonstrated that the axial symmetry of the circular hydraulic jump may be broken, resulting in steady polygonal jumps. In addition to these polygonal forms, our experimen...

We analyze the inertia dominated flow of thin liquid films on microtextured substrates, which here are assemblies of micron-size posts arranged on regular lattices. We focus on situations for which the thin-film thickness and the roughness characteristic length scale are of the same order of magnitude, i.e., a few hundred microns. We assume that the liquid flows isotropically through the roughn...

The flow field past a prosthetic aortic valve comprises many details that indicate whether the prosthesis is functioning well or not. It is, however, not yet fully understood how an optimal flow scenario would look, i.e. which subtleties of the fluid dynamics in place are essential regarding the durability and compatibility of a prosthetic valve. In this study, we measured and analyzed the 3D f...