scholarly journals Dual solution for double-diffusive mixed convection opposing flow through a vertical cylinder saturated in a Darcy porous media containing gyrotactic microorganisms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdulaziz Alsenafi ◽  
M. Ferdows
Keyword(s):  
Porous Media ◽  
Mixed Convection ◽  
Saturated Porous Medium ◽  
Vertical Cylinder ◽  
Dual Solutions ◽  
Energy Concentration ◽  
Convection Flow ◽  
Gyrotactic Microorganisms ◽  
Flow Through ◽  
Fluid Saturated Porous Medium

AbstractThe steady mixed convection flow towards an isothermal permeable vertical cylinder nested in a fluid-saturated porous medium is studied. The Darcy model is applied to observe bioconvection through porous media. The suspension of gyrotactic microorganisms is considered for various applications in bioconvection. Appropriate similarity variables are opted to attain the dimensionless form of governing equations. The resulting momentum, energy, concentration, and motile microorganism density equations are then solved numerically. The resulting dual solutions are graphically visualized and physically analyzed. The results indicate that depending on the systems' parameters, dual solutions exist in opposing flow beyond a critical point where both solutions are connected. Our results were also compared with existing literature.

Stability of Bioconvection in Suspensions of Gyrotactic Microorganisms in Porous Media

2002 ◽  
Author(s):  
A. V. Kuznetsov ◽  
A. A. Avramenko
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Saturated Porous Medium ◽  
Critical Value ◽  
Numerical Results ◽  
Velocity Fluctuations ◽  
Gyrotactic Microorganisms ◽  
Upward Direction ◽  
Upward Velocity ◽  
Fluid Saturated Porous Medium

In this paper, a model of bioconvection in a suspension of gyrotactic motile microorganisms in a fluid saturated porous medium is suggested. The microorganisms considered in this paper are heavier than water and gyrotactic behavior results in their swimming towards the regions of most rapid downflow. Because of that, the regions of downflow become denser than the regions of upflow. Buoyancy increases the upward velocity in the regions of upflow and downward velocity in the regions of downflow, thus enhancing the velocity fluctuations. The experiments performed by Kessler (1986) and the numerical results of Kuznetsov and Jiang (2001) indicate that if the permeability of porous medium is sufficiently small it will prevent the development of convection instability. However, for practical purposes, in order to maximize the flux of the cells in the upward direction it is desirable to have the permeability of the porous medium as high as possible. The aim of this paper is to investigate the value of critical permeability. If permeability is smaller than this critical value bioconvection does not occur and microorganisms simply swim in the upward direction.

scholarly journals Dual Solutions for Opposing Mixed Convection in Porous Media

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Jian-Jun Shu ◽  
Qi-Wen Wang ◽  
Ioan Pop
Keyword(s):  
Mixed Convection ◽  
Saturated Porous Medium ◽  
Dual Solutions ◽  
Convection Boundary Layer ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Convection Boundary ◽  
Fluid Saturated Porous Medium ◽  
Layer Flow ◽  
Convection In Porous Media

The problem of steady mixed convection boundary layer flow on a cooled vertical permeable circular cylinder embedded in a fluid-saturated porous medium is studied. Here, we evaluate the flow and heat transfer characteristics numerically for various values of the governing parameters and demonstrate the existence of dual solutions beyond a critical point.

scholarly journals Dual Solutions in Mixed Convection Flow Along Non-Isothermal Inclined Cylinder Containing Gyrotactic Microorganism

2021 ◽  
Vol 87 (3) ◽  
pp. 51-63
Author(s):  
Nayema Islam Nima ◽  
Mohammad Ferdows
Keyword(s):  
Differential Equations ◽  
Mixed Convection ◽  
Forced Convection ◽  
Transfer Rate ◽  
Vertical Cylinder ◽  
Dual Solutions ◽  
Convection Flow ◽  
Convection Regime ◽  
Linear Ordinary Differential Equations ◽  
Gyrotactic Microorganism

The purpose of this research is to present dual solution for combined free and forced convection flow towards a non-isothermal permeable inclined cylinder containing gyrotactic microorganism. Though several researches were done on dual solutions for mixed convection and also along the vertical cylinder for the numerous engineering applications but very few works have done on dual solutions for mixed convection with gyrotactic microorganisms. Two steps are performed here to carry out numerical calculations. Firstly, the governing partial differential equations are simplified into set of coupled non-linear ordinary differential equations using similarity transformations and then solved numerically using bvp4c function from MATLAB. Dual solutions are observed for heat, mass and density of motile microorganism transfer rate and also for velocity, temperature, concentration, and microorganism profile beyond a critical point. The research is reached to excellent argument by comparison in few cases between the results obtained from MATLAB and Maple algorithm. The heat, mass and motile microorganism transfer rate decreases from free to mixed convection regime and then increases to forced convection regime with the influence of different flow control parameters. The results also indicate that dual solutions for different flow profiles exist only in free convection dominated regime.

Analysis of Energy and Exergy for Mixed Convection Flow in Microstructure Filled Vented Enclosures

2011 ◽  
Author(s):  
Muinul Hasan Banna ◽  
A. K. M. Sadrul Islam ◽  
Abbas S. Milani ◽  
Mina Hoorfar
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Saturated Porous Medium ◽  
Heat Removal ◽  
High Rate ◽  
Convection Flow ◽  
Large Numbers ◽  
Energy And Exergy ◽  
Optimum Heat ◽  
Flow Through

Understanding heat transfer through saturated porous media is of great importance to many engineering and geophysical systems such as cooling the electronic devices and solar power collectors, and post-accidental heat removal in nuclear reactors. Large numbers of research studies have been and are conducted on the expanding field of porous media due to the high rate of heat transfer in these systems. Despite the efforts made towards the study of the mechanics of fluid flow through porous media, little is studied the rate of exergy which is the only factor presenting the rate of reusable energy potentially produced by a heat generating body. The objective of this study is to develop a design of experiment to carry out a numerical analysis of heat transfer in a rectangular enclosure filled with a saturated porous medium. The optimum heat transfer rate will be obtained for various configuration-related parameters, namely different inlet to outlet ratios and different inlet width to cavity width ratios. These parameters will be optimized to achieve maximum rate of heat transfer and minimum rate of entropy generation. The results of this study will also help to determine relationships for predicting the heat transfer characteristics of the enclosure.

Linear Stability Analysis of Bioconvection in Porous Media: The Effect of Fouling

2003 ◽  
Author(s):  
A. V. Kuznetsov ◽  
A. A. Avramenko
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Stability Analysis ◽  
Saturated Porous Medium ◽  
Porous Matrix ◽  
Critical Porosity ◽  
Gyrotactic Microorganisms ◽  
Porosity And Permeability ◽  
Fluid Saturated Porous Medium ◽  
The Stability

In this paper, the effect of fouling on the stability of a uniform suspension of gyrotactic motile microorganisms in a fluid saturated porous medium is investigated. Fouling may occur because of the deposition of microorganisms on a porous matrix. This deposition decreases porosity and permeability of the porous medium. Stability analysis carried out in this paper reveals that there is a critical porosity of the porous medium. If the porous medium utilized for this process has a smaller porosity than critical, the uniform suspension of gyrotactic microorganisms is stable and bioconvection does not develop. If the porous medium has lager porosity than critical, the uniform suspension is unstable and bioconvection develops.

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