Sharif Digital Repository

Natural convection in cavity has become one of the classical heat transfer problems with a large volume of research performed both experimentally and numerically. There are several permutations of the cavity problem related to its shape, its boundary conditions, the properties of circulating fluid, etc. Among them, the most interesting one is that of a rectangular cavity, which is maintained at hot and cold temperatures on its opposing side walls while its horizontal walls are thermally insulated. Contrary to the past works, we study the cavity with small to high temperature differences. This produces a wide range of compressibility effects in the cavity, which need to be treated carefully... 

Cavity flameholder is known as an efficient technique for providing the ignition zone. In this research, computational fluid dynamic is applied to study the influence of the various shapes of cavity as flameholder on the mixing efficiency inside the scramjet. To evaluate different shapes of cavity flame holder, the Reynolds-averaged Navier–Stokes equations with (SST) turbulence model are solved to reveal the effect of significant parameters. The influence of trapezoidal, circle and rectangular cavity on fuel distribution is expansively analyzed. Moreover, the influence of various Mach numbers (M = 1.2, 2 and 3) on mixing rate and flow feature inside the cavity is examined. The comprehensive... 

In this paper, we present a design method of dual-band waveguide rectangular cavity filters, with a series in-line topology. The coupling matrix is based on asynchronously tuned designs, where two sets of resonances exist for the two bands. Thus the filter is inherently different than the typical dual-band designs in the literature, as existing designs utilize resonators at the same frequency. The design at Ku band validates the underlying idea and concept, and the theory of the detuned coupling matrix. This rectangular waveguide implementation can provide noticeable miniaturization in applications with high-power requirements  

The present simulation aims to investigate adding NEPCM nanoparticles to water in the natural convection inside a cavity by using FVM method and SIMPLE algorithm. Nano-encapsulated phase change material (NEPCM) consists of a shell and core with phase change property. The NEPCM particles in base fluid have the ability to transfer heat by absorbing and dissipating heat in the liquid-solid phase change state. In this study, the energy wall phenomenon due to the phase change of NEPCM core has appeared that the whose energy transfer strength is proportional to the latent heat of NEPCM core and the thickness of the energy wall. Moreover, the relationship between the energy wall and the heat...