Lower Wall Of Cavity Research Articles

Modelling of thermal energy individualities in novel enclosure with uniformly heated circular obstacle and multi-shaped heated ribs

The thermal flow field of Newtonian fluid in novel cavity is investigated numerically. The three different shaped heated ribs namely triangular, rectangular and circular are installed case-wise at lower wall of cavity. The uniformly heated circular cylinder is taken fixed in center of cavity for each case. The no-slip condition is imposed on both the top wall and exterior surface obstacle. The fluid enters from the inlet of a cavity with a specific velocity profile. At outlet, a Neumann condition is taken. The upper wall, inlet and outlet of cavity are taken cold. Thermal flow field individualities are explored by using the energy, momentum and continuity equations. The finite element approach is used to solve these equations. The contour plots, line graphs and tabular data are used to report the ultimate observations on velocity, pressure, temperature and hydrodynamic forces. Particularly, the lift and drag coefficient values are obtained via line integration. The variations pattern in Nusselt for triangular, rectangular and circular ribs at lower wall are shared. It is noticed that the coefficients values towards heated obstacle are higher in magnitude for the case of heated rectangular rib as compared to heated triangular and circular ribs.

The investigation of thermal radiation and free convection heat transfer mechanisms of nanofluid inside a shallow cavity by lattice Boltzmann method

This paper aims to simulate the interaction between thermal surface radiation and nanofluid free convection in a two dimensional shallow cavity by lattice Boltzmann method. The supposed nanofluid is generated by a homogeneous mixture of water and nanoparticles of Al2O3. The upper and lower walls of cavity are maintained at cold and hot temperature, respectively; while the side walls are kept thermally insulated. The cavity aspect ratio is chosen as 5 which indicates a shallow one. The cavity all inner surfaces are considered as the gray diffuse emitters and reflectors of radiation. The computations are performed for the wide range of parameters as Ra = 104 and Ra = 105; ε=0.5 and ε=0.9 while nanoparticles volume fraction changes between 0.0≤φ≤0.04 at each case. As a result, the effects of emissivity and Rayleigh number are studied on the total heat transfer of radiation and free convection of nanofluid. The suitable validations are examined beside the useful grid study procedure. The results are presented as the profiles of velocity and temperature and also the streamlines and isotherms. Moreover the local and averaged Nusselt numbers are provided for the coupled and uncoupled states of radiation and free convection heat transfer mechanisms. It is seen that Num of total free convection and radiation would be more at higher Ra and ε; which indicates that radiation heat transfer coupled with free convection might affect the flow field and improve the Nusselt number.

Study of Free Convection in a Square Cavity with Magnetic Field and Semi Circular Heat Source of Different Orientations

Free convection flow in the presence of magnetic field in a square cavity with semi circular heat source was studied in this paper. The lower wall of cavity was heated from below and upper wall of cavity was cold whereas side walls of the cavity were thermally insulated. The governing differential equations are solved by finite element method. The effects of magnetic field were studied on flow and temperature field and heat transfer performance at a wide range of parameter Hartmann (0≤Ha≤100) number. The study is performed for different orientation of heated solid and Hartmann numbers at Pr=0.71 and (10≤Ra≤10000).