The oscillatory response of multiple shock waves to upstream disturbances in a supersonic flow is studied numerically constant area rectangular duct. accelerated through nozzle with an exit Mach number 1.75 and continues the duct, where are formed. To investigate effect disturbance on oscillations, three parameters varied systematically: turbulent intensity, frequency pressure fluctuation, ampl...

Large-eddy simulations are used to demonstrate the effects of Rayleigh-Taylor instabilities (RTIs) on constant-pressure, turbulent premixed flames stabilized in a curved rectangular duct. A splitter plate constant radius separates reactant and pilot stream such that flame stabilizes mixing layer between two streams. Centrifugal acceleration due duct curvature induces RTI, increasing higher-dens...

A simple theory is described for the transmission of low frequency sound through the walls of rectangular ducts, particularly those in air conditioning systems. The model is based on a coupled acoustic/structural wave system, and it is assumed that the duct radiates in the same way as a finite-length line source incorporating a single travelling wave. Measurements of wall transmission loss on t...

The sound properties along a long rectangular enclosure with a circular source on the top wall and rectangular opening at the side wall are studied. A mathematical model of average pressure at an opening contributed by the sound source and assuming air piston at the opening is derived in terms of the acoustic mode for a rigid duct. Three-dimensional numerical modelling is conducted to compare t...

In this paper, we investigate the effects of small boundary perturbation on the laminar motion of a conducting fluid in a rectangular duct under applied transverse magnetic field. A small boundary perturbation of magnitude ǫ is applied on cross-section of the duct. Using the asymptotic analysis with respect to ǫ, we derive the effective model given by the explicit formulae for the velocity and ...

This paper presents the study of fluid flow and heat transfer in a plain rectangular duct of a solar air heater by using Computational Fluid Dynamics (CFD). The effect of Reynolds number on heat transfer coefficient and friction factor was investigated. A commercial finite volume package ANSYS FLUENT 12.1 is used to analyze and visualize the nature of the flow across the duct of a solar air hea...

In this article some analytic expressions for acoustic propagation in 3-D ducts of rectangular cross-section and with flexible walls are explored. Consideration is first given to the propagation of sound in an unlined 3-D duct formed by three rigid walls and closed by a thin elastic plate. An exact closed form expression for the fluid-structure coupled waves is presented. The effect of incorpor...

The present paper describes how to apply the Chebyshev orthogonal collocation technique to solve steady-state and unsteady-steady two-dimensional problems. All problems are solved using one single computer algebra, Mathematica . The problems include: (1) steady-state heat transfer in a rectangular bar, (2) steady-state flow in a rectangular duct, (2) steady-state heat transfer in a cooling cyli...