A numerical investigation of entropy generation in laminar forced convection of gas flow over a backward facing step in a horizontal duct under bleeding condition is presented. For calculation of entropy generation from the second law of thermodynamics in a forced convection flow, the velocity and temperature distributions are primary needed. For this purpose, the three-dimensional Cartesian co...

In the present paper suboptimal boundary control strategies for the time-dependent, incompressible flow over the backward-facing step are considered. The objective consists in the reduction of the recirculation bubble of the flow behind the step. Several cost functionals are suggested and a frame for the derivation of the optimality systems for a general class of cost functionals is presented. ...

Efficient, nonlinearly stable entropic lattice Boltzmann models for computational fluid dynamics are presented. A new method of fast evaluation of equilibria to machine precision is proposed. Analytical solution is found for the collision step which guarantees stability and thermodynamic consistency of the scheme. As an example, a novel 15-velocity lattice Boltzmann model is derived and validat...

A novel high-resolution Navier-Stokes method is proposed for modelling large-scale turbulent flows. The method is based on the non-oscillatory low-dissipative and low-dispersive CABARET scheme. Numerical results are provided for the classical backward-facing step problem and for the recent OECD/NEA-Vattenfall T-junction blind-test exercise.

PURPOSE This study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD). METHODS 2D particle image velocimetry measurements were conducted on region (x/h = 0-2.25) and reattachment zone in...

Abstract

The two-phase flow generated behind a cavitating backward-facing step is studied using the combination of three experimental techniques: wall-pressure measurements, global high-speed imaging with visible light, and high spatial temporal resolution x-ray imaging. Three zones are identified based on topology vapor fraction maps, that correspond to vaporization, transport, condensation. Simultaneo...