Investigation of nanofluid mixed convection in a shallow cavity using a two-phase mixture model

Application of nanofluids in heat transfer enhancement is prospective. They are solid/liquid suspensions of higher thermal conductivity and viscosity compared to common working fluids. A number of ...

https://journals.sagepub.com/doi/pdf/10.1177/1687814016673569

A survey on experimental and numerical studies of convection heat transfer of nanofluids inside closed conduits

In the present study, a numerical analysis is performed to understand the mixed convection flow, and heat and mass transfer with Soret effect in a two-sided lid-driven square cavity. The horizontal walls of the cavity are adiabatic and impermeable, while vertical walls are kept at constant but different temperatures and concentrations. The vertical walls move in a constant velocity. According to the direction of the movement of walls, three cases have been studied for different combinations of parameters involved in the study. The governing unsteady equations are solved numerically by the finite volume method with the SIMPLE algorithm. The results are presented graphically in the form of streamlines, isotherms, and velocity profiles. Heat and mass transfer rates are reduced if both walls are moving the in same direction, while heat and mass transfer rates are enhanced if the walls are moving in the opposite direction.

Numerical Study on Double Diffusive Mixed Convection with a Soret Effect in a Two-Sided Lid-Driven Cavity

Two-dimensional numerical simulation is performed for the hydromagnetic mixed convective transport in a vertical lid-driven square enclosure filled with an electrically conducting fluid in the presence of a heat conducting and rotating solid circular cylinder. Both the top and bottom horizontal walls of the enclosure are considered thermally insulated, and the left and right vertical walls are kept isothermal with different temperatures. The left wall is moving in the upward direction at a uniform speed, while all other walls are stationary. A uniform magnetic field is applied along the horizontal direction normal to the moving wall. A heat conducting circular cylinder is placed centrally within the outer enclosure. The cylinder is made to rotate in its own plane about its centroidal axis. Both the clockwise and counterclockwise rotations of the cylinder are considered. All solid walls are assumed electrically insulated. Simulations are performed for various controlling parameters, such as the Richardson ...

Hydromagnetic Mixed Convective Transport in a Vertical Lid-Driven Cavity Including a Heat Conducting Rotating Circular Cylinder

Mechanobiology of low-density lipoprotein transport within an arterial wall—Impact of hyperthermia and coupling effects

Mixed convection in an obstructed cavity with heated horizontal walls is investigated in this work. Brinkman-Forchheimer-extended Darcy model is utilized to describe the flow characteristics within a porous medium for different angles of attack with respect to the forced convection. Numerical results are obtained for a wide range of Grashof numbers (102–109), Reynolds numbers (102–105), Darcy numbers (10−6–10−1), and aspect ratios (0.25–2). Effects of the pertinent physical parameters are investigated in terms of the flow and temperature fields, as well as Nusselt number distributions. The presented results show that the Darcy number plays a significant role on the flow and thermal fields and the Nusselt number distributions for different flow configurations. For an inclined flow, the vertical velocity component is substantially diminished within a narrow entrance section near the inlet boundary. It is shown that as the aspect ratio increases the thickness of the thermal boundary layer increases, resultin...

Mixed Convection in an Obstructed Open-Ended Cavity

A novel area-averaged dielectric conformal technique combined with the finite-difference time-domain (FDTD) method has been investigated in accuracy and efficiency for modeling curved dispersive medium objects in this article. The proposed method utilizes an effective average dielectric constant, which is derived by area averages of different dielectric regions in irregular cells cut by curved surfaces, to modify the magnetic field updating equations in auxiliary differential equation FDTD method. The accuracy and efficiency of the method are verified by comparing the radar cross section results produced by the method of moments and the FDTD method with very fine meshes, respectively. Numerical results show that good agreements can be achieved by using coarse mesh size (12 cells per wavelength). Further, the proposed method is devoted to analyzing the bio-electromagnetic effects of a dispersive human body in a vehicle platform to show its good ability in solving such complex problems.

An Area-Averaged Conformal Technique for the Electromagnetic Simulations of Debye Medium

In order to investigate the electromagnetic (EM) propagation characteristics and further get the channel models for indoor environments, a modified conformal finite‐difference time‐domain (CFDTD) method is introduced in this paper. Specifically, the dispersion characteristics of media are modeled by using the auxiliary differential equation (ADE) technique of the Debye model, and the EM field iterative equation is obtained by weighted‐length of various media in the conformal cells for the curved structure. The proposed method is used to simulate the channels of 2.4 GHz wireless fidelity (Wi‐Fi) network and 5G microcellular network, respectively, for the single‐ and complex multi‐room scenarios. The impulse response, power delay profile and path loss exponent are extracted from the simulation data to analyze the effective ultra‐wideband (UWB) channel characteristics. Compared with the traditional FDTD, the proposed method has the advantage of obtaining a stable and good accuracy solution and reducing the time step without the need to solve high‐order differential equations.

Wenlu Shi

Papers

Mixed Convection in an Obstructed Open-Ended Cavity

An Area-Averaged Conformal Technique for the Electromagnetic Simulations of Debye Medium

Modeling of indoor network channels with dispersive media based on a modified CFDTD method