Abstract: A numerical study is made in a parallel-plate porous
channel subjected to an oscillating flow and an exothermic chemical
reaction on its walls. The flow field in the porous region is modeled
by the Darcy–Brinkman–Forchheimer model and the finite volume
method is used to solve the governing equations. The effects of the
modified Frank-Kamenetskii (FKm) and Damköhler (Dm) numbers,
the amplitude of oscillation (A), and the Strouhal number (St) are
examined. The main results show an increase of heat and mass
transfer rates with A and St, and their decrease with FKm and Dm.
Abstract: MHD chemically reacting viscous fluid flow towards
a vertical surface with slip and convective boundary conditions has
been conducted. The temperature and the chemical species
concentration of the surface and the velocity of the external flow are
assumed to vary linearly with the distance from the vertical surface.
The governing differential equations are modeled and transformed
into systems of ordinary differential equations, which are then solved
numerically by a shooting method. The effects of various parameters
on the heat and mass transfer characteristics are discussed. Graphical
results are presented for the velocity, temperature, and concentration
profiles whilst the skin-friction coefficient and the rate of heat and
mass transfers near the surface are presented in tables and discussed.
The results revealed that increasing the strength of the magnetic field
increases the skin-friction coefficient and the rate of heat and mass
transfers toward the surface. The velocity profiles are increased
towards the surface due to the presence of the Lorenz force, which
attracts the fluid particles near the surface. The rate of chemical
reaction is seen to decrease the concentration boundary layer near the
surface due to the destructive chemical reaction occurring near the
surface.
Abstract: Numerical study of two dimensional supersonic
hydrogen-air mixing layer is performed to investigate the effect of
turbulence and chemical additive on ignition distance. Chemical
reaction is treated using detail kinetics. Advection upstream splitting
method is used to calculate the fluxes and one equation turbulence
model is chosen here to simulate the considered problem. Hydrogen
peroxide is used as an additive and the results show that inflow
turbulence and chemical additive may drastically decrease the
ignition delay in supersonic combustion.
Abstract: The paper presents an analytical solution for dispersion
of a solute in the peristaltic motion of a micropolar fluid in the
presence of magnetic field and both homogeneous and heterogeneous
chemical reactions. The average effective dispersion coefficient has
been found using Taylor-s limiting condition under long wavelength
approximation. The effects of various relevant parameters on the average
coefficient of dispersion have been studied. The average effective
dispersion coefficient increases with amplitude ratio, cross viscosity
coefficient and heterogeneous chemical reaction rate parameter. But it
decreases with magnetic field parameter and homogeneous chemical
reaction rate parameter. It can be noted that the presence of peristalsis
enhances dispersion of a solute.
Abstract: Polyurethane foams (PUF) were formed by a chemical
reaction of polyol and isocyanate. The polyol was manufactured by
ring-opening hydrolysis of epoxidized soybean oil in the presence of
phosphoric acid under varying experimental conditions. Other
factors in the foam formulation such as water content and surfactant
were kept constant. The effect of the amount of solvents, phosphoric
acid, and their derivates in the foam formulation on the properties of
polyurethane foams were studied. The properties of the material were
measured via a number of parameters, which are water content of
prepared polyol, polymer density and cellular structures.
Abstract: Polyurethane foam (PUF) is formed by a chemical
reaction of polyol and isocyanate. The aim is to understand the
impact of Silicone on synthesizing polyurethane in differentiate
volume of molding. The method used was one step process, which is
simultaneously caried out a blending polyol (petroleum polyol and
soybean polyol), a TDI (2,4):MDI (4,4-) (80:20), a distilled water,
and a silicone. The properties of the material were measured via a
number of parameters, which are polymer density, compressive
strength, and cellular structures. It is found that density of
polyurethane using silicone with volume of molding either 250 ml or
500 ml is lower than without using silicone.