Linear stability of a double diffusive layer with variable fluid properties

1995 ◽  
Vol 38 (9) ◽  
pp. 1683-1691 ◽  
Author(s):  
Josef Tanny ◽  
Victor A. Gotlib
Keyword(s):  
Linear Stability ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Diffusive Layer ◽  
Double Diffusive

scholarly journals Effects of Variable Fluid Properties on Double Diffusive Mixed Convection with Chemical Reaction Over an Accelerating Surface

2021 ◽  
Vol 12 (4) ◽  
pp. 5161-5173
Keyword(s):  
Differential Equations ◽  
Chemical Reaction ◽  
Variable Viscosity ◽  
Nonlinear Partial Differential Equations ◽  
Flow Characteristics ◽  
Physical Parameters ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Mixed Convective Flow ◽  
Double Diffusive

In this study, we investigate the effect of variable fluid properties such as variable viscosity, porosity, permeability, thermal conductivity, and solutal diffusivity on double-diffusive mixed convective flow over an accelerating surface under the influence of a higher-order chemical reaction. The governing equations of the physical problem involve a coupled nonlinear partial differential equations and which are transformed into a coupled nonlinear ordinary differential equations using a suitable similarity transformation. Numerical computation using shooting technique is adopted to study the physical characteristics of velocity, temperature and concentration for various values of non-dimensional parameters like Prandtl number, Eckert number, buoyancy parameters, viscosity parameter, porous parameter, a ratio of thermal conductivities, a ratio of solutal diffusivities and chemical reaction parameter etc are involved in the problem. The computed numerical results are presented in the graphs to illustrate the details of the flow characteristics and their dependence on physical parameters. Our computed results are compared with earlier works of Seddeek in the absence of a magnetic field and found in good agreement.

scholarly journals Turbulence kinetic energy exchanges in flows with highly variable fluid properties

2017 ◽  
Vol 834 ◽  
pp. 5-54 ◽  
Author(s):  
Dorian Dupuy ◽  
Adrien Toutant ◽  
Françoise Bataille
Keyword(s):  
Reynolds Number ◽  
Temperature Gradient ◽  
Velocity Fluctuation ◽  
Spectral Studies ◽  
Spectral Energy ◽  
Correlation Tensor ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Energy Exchanges ◽  
The Mean

This paper investigates the energy exchanges associated with the half-trace of the velocity fluctuation correlation tensor in a strongly anisothermal low Mach fully developed turbulent channel flow. The study is based on direct numerical simulations of the channel within the low Mach number hypothesis and without gravity. The overall flow behaviour is governed by the variable fluid properties. The temperature of the two channel walls are imposed at 293 K and 586 K to generate the temperature gradient. The mean friction Reynolds number of the simulation is 180. The analysis is carried out in the spatial and spectral domains. The spatial and spectral studies use the same decomposition of the terms of the evolution equation of the half-trace of the velocity fluctuation correlation tensor. The importance of each term of the decomposition in the energy exchanges is assessed. This lets us identify the terms associated with variations or fluctuations of the fluid properties that are not negligible. Then, the behaviour of the terms is investigated. The spectral energy exchanges are first discussed in the incompressible case since the analysis is not present in the literature with the decomposition used in this study. The modification of the energy exchanges by the temperature gradient is then investigated in the spatial and spectral domains. The temperature gradient generates an asymmetry between the two sides of the channel. The asymmetry can in a large part be explained by the combined effect of the mean local variations of the fluid properties, combined with a Reynolds number effect.

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