in the computational fluid dynamics (cfd) modeling of gas-solids two phase flow, the effect of boundary conditions play an important role in predicting the hydrodynamic characteristics of fluidized beds. in this work, the hydrodynamics of conical fluidized bed containing dried tio2 nano-agglomerates were studied both experimentally and computationally. the pressure drop was obtained by pressure...

In this paper we discuss a new approach to the quasinormal-mode problem in general relativity. By combining a characteristic formulation of the perturbation equations with the integration of a suitable phase-function for a complex valued radial coordinate, we reformulate the standard outgoing-wave boundary condition as a zero Dirichlet condition. This has a number of important advantages over p...

During the last few years, a number of numerical boundary condition schemes have been used to study various aspects of the no-slip wall condition using the lattice Boltzmann method. In this paper, a modified boundary condition method is employed to simulate the no-slip wall condition in the presence of the body force term near the wall. These conditions are based on the idea of the bounce-back ...

on the basis of the steady-state two-dimensional theory of thermoelasticity, stress field around various holes in infinite isotropic plate is discussed. the plate is subjected to uniform heat flux and thermal insulated condition along the hole boundary is assumed. by using the complex potential functions and by applying the conformal mapping and solving the integral equations, the effect of blu...

We propose a geometric multigrid method for solving linear systems arising from irregular boundary problems involving multiple interfaces in two and three dimensions. In this method, we adopt a matrix-free approach; i.e., we do not form the fine grid matrix explicitly and we never form nor store the coarse grid matrices, as many other robust multigrid methods do. The main idea is to construct a...

The performance of acoustic treatments installed on aircraft engines is strongly influenced by the boundary layer of the grazing flow on the surface of the liner. The parametric study presented in this paper illustrates the extent of this effect and identifies when it is significant. The acoustic modes of a circular duct with flow are calculated using a finite sound fields found in current turb...

In this study, we proposed a novel scheme for the implementation of the no-slip boundary condition in thelattice Boltzmann method (LBM) . In detail , we have substituted the classical bounce-back idea by the direct immersed boundary specification . In this way we construct the equilibrium density functions in such a way that it feels the no-slip boundaries . Therefore , in fact a kind of equili...

On-site boundary conditions are often desired for lattice Boltzmann simulations of fluid flow in complex geometries such as those of porous media or microfluidic devices. The possibility of specifying the exact position of the boundary, independently of other simulation parameters, simplifies the analysis of the system. For practical applications it should allow one to freely specify the direct...

in this study, we proposed a novel scheme for the implementation of the no-slip boundary condition in thelattice boltzmann method (lbm) . in detail , we have substituted the classical bounce-back idea by the direct immersed boundary specification . in this way we construct the equilibrium density functions in such a way that it feels the no-slip boundaries . therefore , in fact a kind of equili...