Papers by Keyword: Channel Flow

Abstract: The transient dynamics of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar flow of a Newtonian liquid flowing through a rectangular channel is investigated. The Boussinesq approximation is assumed for the density variation with pollutant concentration. The governing equations of mass and momentum conservation are coupled to the pollutant concentration equation as well as to the viscoelastic constitutive model for the polymer stresses. The Oldroyd-B viscoelastic constitutive model is employed to model the deformation and characteristics of the polymer stresses. The coupled system of nonlinear partial differential equations is solved numerically using robust and efficient semi-implicit finite difference methods (FDM). Solutions are presented in graphical form for various parameter values. The model can be a useful tool in understanding the dynamics of domestic and industrial pollution situations that may arise from improper discharge of long-chain hydrocarbon products into, say, water drainage systems. The novelty of this investigation is in the modelling of the long-chain hydrocarbon-product pollutants via appropriate viscoelastic (polymeric) constitutive equations. In general, it is observed that parameters which increase (decrease) the flow velocity correspondingly increase (respectively decrease) the wall shear stress. Similarly, it is observed that parameters which increase (decrease) the polymer concentration correspondingly increase (respectively decrease) the mass transfer rates. The wall shear stress and mass transfer are measurable quantities. In this respect, our work offers such measurements as predictive tools to detect the scale of contamination.

Abstract: In this paper, rheology of laminar incompressible Copper-Kerosene nanofluid in a channel with stretching walls under the influence of transverse magnetic field is investigated. The main structure of the partial differential equations was taken from the law of conservation of mass, momentum and energy equations. Governing boundary layer equations are transformed into nonlinear ordinary differential equations by using similarity variables and then solved with 3-stage Lobatto IIIA formula. Numerical results were compared with another numerical method (Runge-Kutta-Fehlberg) and found excellent agreement. The influence of physical parameters Reynolds number, magnetic number, solid volume fraction, momentum and thermal slip parameters on velocity and temperature profile considered. Numerical results revealed that solid volume fraction decreases the velocity of nanofluid particles near the lower wall of the channel and increase the thermal boundary layer thickness in the channel.

Abstract: In this paper, both first and second laws of thermodynamics are employed to investigate the combined effects of magnetic field, buoyancy force, velocity slip, suction/injection, porous medium permeability, thermal radiation absorption, viscous and Joule heating on mixed convective flow of an electrical conducting Casson fluid in a vertical channel. The dimensionless governing equations are obtained and solved numerically using a shooting technique coupled with a fourth order Runge-Kutta-Fehlberg integration scheme. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number are presented graphically and discussed quantitatively. It is found that with appropriate combination of thermophysical parameter values the entropy generation rate in the presence of an applied magnetic field can successfully.

Abstract: The magneto-hemodynamic laminar flow of a conducting incompressible viscous nanofluid (blood) through a channel of slowly varying width under a transverse magnetic is investigated using perturbation and numerical methods. For this purpose, Buongiorno’s model is employed for the analysis in four different channels namely, convergent, divergent, locally constricted and wavy channels. Oberbeck-Boussinesq approximation is used and the partial differential equations are solved using perturbation series method. For validation, the governing differential equations are also solved numerically. Both perturbation and numerical results are compared and are found in good agreement. The effects of pertinent parameters on the fluid flow, heat and mass transfer in the selected channels are analyzed for special cases. The results show that both thermal and solutal Richardson numbers have opposite behaviour for skin friction, heat and mass transfer in each channel.

Abstract: In this article, we present a lattice Boltzmann method to treat moving solid particles in a fluid. The scheme uses a uniform Eulerian grid for the flow domain and a Lagrangian grid to trace the dynamics of solid particles. The solid particles in a cavity located on a floor of straight channel were simulated at two difference aspect ratio and wide range of Reynolds numbers. Two different shapes of cavity were selected to investigate their effect of the efficiency of solid particle removal. Current study found that the rate of particle removal is significantly dependence on the Reynolds number of the flow and the shape of the cavity. Excellent agreement with the results computed by other methods indicates the capability of the scheme in predicting particulate problem.

Abstract: In this paper, Constrained Interpolated Profile Method (CIP) was used to simulate contaminants removal from square cavity in channel flow. Predictions were conducted for the range of aspect ratios from 0.25 to 4.0. The inlet parabolic flow with various Reynolds number from 50 to 1000 was used for the whole presentation with the same properties of contaminants and fluid. The obtained results indicated that the percentage of removal increased at high aspect ratio of cavity and higher Reynolds number of flow but it shows more significant changes as increasing aspect ratio rather than increasing Reynolds number. High removal rate was found at the beginning of the removal process.

Abstract: In this work, the application of Generalized Differential Quadrature Method (GDQM) to solve a variable viscosity channel flow under constant magnetic field is investigated. The governing equations for channel flow in between two infinite horizontal parallel porous plates subject to convective surface boundary conditions are given in dimensional and non-dimensional forms, pointing out the dimensionless parameters used. These equations are discretized using the GDQM, and solved via Newton Raphson Method. Effects of magnetic field on incompressible electrically conducting fluid velocity and temperature profiles are presented in plots.

Abstract: In this paper the numerical modelling of the behaviour of a channel of a hygroscopic compact matrix is presented. The heat and mass transfer phenomena occurring in the porous medium and within the airflow are strongly coupled, and some properties of the airflow and of the desiccant medium exhibit important changes during the sorption/desorption processes. The adopted physical modelling takes into account the gas side and solid side resistances to heat and mass transfer, as well as the simultaneous heat and mass transfer together with the water adsorption/desorption process in the wall domain. Two phases co-exist in equilibrium inside the desiccant porous medium, the equilibrium being characterized by sorption isotherms. The airflow is treated as a bulk flow, the interaction with the wall being evaluated by using appropriated convective coefficients. The model is used to perform simulations considering two distinct values of the channel wall thickness and different lengths of the channel. The results of the modelling lead to a good understanding of the relationship between the characteristics of the sorption processes and the behaviour of hygroscopic matrices, and provide guidelines for the wheel optimization, namely of the duration of the adsorption and desorption periods occurring in each hygroscopic channel.