Finite-amplitude acoustic traveling waves in a fluid that saturates a porous medium: Acceleration wave formation

2006 ◽  
Vol 355 (3) ◽  
pp. 216-221 ◽  
Author(s):  
P.M. Jordan
Keyword(s):  
Porous Medium ◽  
Traveling Waves ◽  
Finite Amplitude ◽  
Wave Formation ◽  
Acceleration Wave

scholarly journals Unsteady Finite Amplitude Convection of Water–Copper Nanoliquid in High-Porosity Enclosures

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
P. G. Siddheshwar ◽  
K. M. Lakshmi
Keyword(s):  
Porous Medium ◽  
Heat Transport ◽  
Heat Storage ◽  
Finite Amplitude ◽  
High Porosity ◽  
Two Phase ◽  
Onset Of Convection ◽  
Maximum Heat ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Unicellular Rayleigh–Bénard convection of water–copper nanoliquid confined in a high-porosity enclosure is studied analytically. The modified-Buongiorno–Brinkman two-phase model is used for nanoliquid description to include the effects of Brownian motion, thermophoresis, porous medium friction, and thermophysical properties. Free–free and rigid–rigid boundaries are considered for investigation of onset of convection and heat transport. Boundary effects on onset of convection are shown to be classical in nature. Stability boundaries in the R1*–R2 plane are drawn to specify the regions in which various instabilities appear. Specifically, subcritical instabilities' region of appearance is highlighted. Square, shallow, and tall porous enclosures are considered for study, and it is found that the maximum heat transport occurs in the case of a tall enclosure and minimum in the case of a shallow enclosure. The analysis also reveals that the addition of a dilute concentration of nanoparticles in a liquid-saturated porous enclosure advances onset and thereby enhances the heat transport irrespective of the type of boundaries. The presence of porous medium serves the purpose of heat storage in the system because of its low thermal conductivity.

Poroacoustic acceleration waves

2006 ◽  
Vol 462 (2075) ◽  
pp. 3493-3499 ◽  
Author(s):  
M Ciarletta ◽  
B Straughan
Keyword(s):  
Porous Medium ◽  
Acoustic Waves ◽  
Building Industry ◽  
Acceleration Wave ◽  
Acceleration Waves ◽  
Continuum Thermodynamic ◽  
Thermodynamic Derivation

A model for acoustic waves in a porous medium is investigated. Due to the use of lighter materials in modern buildings and noise concerns in the environment, such models for poroacoustic waves are of much interest to the building industry. The model has been investigated in some detail by P. M. Jordan. Here we present a rational continuum thermodynamic derivation of the Jordan model. We then present results for the amplitude of an acceleration wave making no approximations whatsoever.

The Influence of Coupled Molecular Diffusion on Double-Diffusive Convection in a Porous Medium

1986 ◽  
Vol 108 (4) ◽  
pp. 872-876 ◽  
Author(s):  
N. Rudraiah ◽  
M. S. Malashetty
Keyword(s):  
Porous Medium ◽  
Molecular Diffusion ◽  
Normal Mode Analysis ◽  
Finite Amplitude ◽  
Mode Analysis ◽  
Double Diffusive Convection ◽  
Amplitude Analysis ◽  
Cross Diffusion ◽  
Diffusive Convection ◽  
Double Diffusive

The effect of coupled molecular diffusion on double-diffusive convection in a horizontal porous medium is studied using linear and nonlinear stability analyses. In the case of linear theory, normal mode analysis is employed incorporating two cross diffusion terms. It is found that salt fingers can form by taking cross-diffusion terms of appropriate sign and magnitude even when both concentrations are stably stratified. The conditions for the diffusive instability are compared with those for the formation of fingers. It is shown that these two types of instability will never occur together. The finite amplitude analysis is used to derive the condition for the maintenance of fingers. The stability boundaries are drawn for three different combinations of stratification and the effect of permeability is depicted.

Finite amplitude analysis of non-isothermal parallel flow in a vertical channel filled with a highly permeable porous medium

2018 ◽  
Vol 857 ◽  
pp. 469-507 ◽  
Author(s):  
Abhishek K. Sharma ◽  
Manish K. Khandelwal ◽  
P. Bera
Keyword(s):  
Porous Medium ◽  
Energy Spectrum ◽  
Kinetic Energy ◽  
Critical Point ◽  
Bifurcation Point ◽  
Vertical Channel ◽  
Finite Amplitude ◽  
Parallel Flow ◽  
Kinetic Energy Spectrum ◽  
Nonlinear Kinetic

This paper addresses the finite amplitude instability of stably stratified non-isothermal parallel flow in a vertical channel filled with a highly permeable porous medium. A cubic Landau equation is derived to study the limiting value of growth of instabilities under nonlinear effects. The non-Darcy model is considered to describe the flow instabilities in a porous medium. The nonlinear results are presented for air as well as water. The analysis is carried out in the vicinity of as well as away from the critical point (bifurcation point). It is found that when the medium is saturated by water then supercritical bifurcation is the only type of bifurcation at and beyond the bifurcation point. However, for air, depending on the strength of the flow and permeability of the medium, both supercritical and subcritical bifurcations are observed. The influence of nonlinear interaction of different harmonics on the heat transfer rate, friction coefficient, nonlinear kinetic energy spectrum and disturbance flow is also studied in both supercritical as well as subcritical regimes. The variation of neutral stability curves of parallel mixed convection flow of air with wavenumber reveals that a bifurcation that is supercritical for some wavenumber may be subcritical orvice versaat other nearby wavenumbers. The analysis of the nonlinear kinetic energy spectrum of the fundamental disturbance also supports the existence of supercritical/subcritical bifurcation at and away from the critical point. The effect of different harmonics on the pattern of secondary flow, based on linear stability theory, is also studied and a significant influence is found, especially in the subcritical regime.

The effects of temperature-dependent viscosity and the instabilities in convection rolls of a layer of fluid-saturated porous medium

1989 ◽  
Vol 206 ◽  
pp. 497-515 ◽  
Author(s):  
A. C. Or
Keyword(s):  
Porous Medium ◽  
Variable Viscosity ◽  
Saturated Porous Medium ◽  
Horizontal Layer ◽  
Finite Amplitude ◽  
Mean Flow ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Fluid Saturated Porous Medium ◽  
Dependent Viscosity

Convection of two-dimensional rolls in an infinite horizontal layer of fluid-saturated porous medium heated from below is studied numerically. Several important finite-amplitude states are isolated, and their bifurcation properties are shown. Effects of the temperature-dependent viscosity are included. The stability of these states is investigated with respect to the class of disturbances that have a ½π phase shift relative to the basic state. In particular, the oscillatory mechanism and the mean-flow generating mechanism through the variable viscosity are discussed.

Sign in / Sign up

Export Citation Format

Share Document