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.

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.

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.

A Theoretical Prediction of Laminar Falling Plumes in Bioconvection of Oxytactic Bacteria in Porous Media

2003 ◽  
Author(s):  
A. V. Kuznetsov ◽  
A. A. Avramenko ◽  
P. Geng
Keyword(s):  
Boundary Layer ◽  
Porous Medium ◽  
Porous Media ◽  
Bacillus Subtilis ◽  
Saturated Porous Medium ◽  
Lower Region ◽  
Oxygen Gradient ◽  
Oxygen Oxygen ◽  
Fluid Saturated Porous Medium ◽  
Upper Boundary

The objective of this paper is to investigate theoretically laminar falling bioconvection plumes in a deep chamber filled with a fluid saturated porous medium. A suspension of motile oxytactic bacteria, such as Bacillus subtilis, which swim up the oxygen gradient, is considered. In a deep chamber, because of the limited diffusivity of oxygen, oxygen concentration is high only in a thin cell-rich upper boundary layer. Since bacteria are heavier than water, the cell-rich upper boundary layer becomes unstable and bioconvection plumes develop. The bioconvection plume carries oxygen and cells from this cell-rich upper boundary layer to the lower region of the chamber.

Dimensionless Scaling Parameters During Thermal Flooding Process in Porous Media

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
M. Enamul Hossain
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Oil Recovery ◽  
Saturated Porous Medium ◽  
Physical Models ◽  
Dimensionless Numbers ◽  
Reservoir Properties ◽  
Fluid Saturated Porous Medium ◽  
Prandtl Numbers ◽  
And Performance

The scaling concept is important, effective, and consistent in any application of science and engineering. Scaled physical models have inimitable advantages of finding all physical phenomena occurring in a specific process by transforming parameters into dimensionless numbers. This concept is applicable to thermal enhanced oil recovery (EOR) processes where continuous alteration (i.e., memory) of reservoir properties can be characterized by various dimensionless numbers. Memory is defined as the continuous time function or history dependency which leads to the nonlinearity and multiple solutions during modeling of the process. This study critically analyzed sets of dimensionless numbers proposed by Hossain and Abu-Khamsin in addition to Nusselt and Prandtl numbers. The numbers are also derived using inspectional and dimensional analysis (DA), while memory concept is used to develop some groups. In addition, this article presents relationships between different dimensionless numbers. Results show that proposed numbers are measures of thermal diffusivity and hydraulic diffusivity of a fluid in a porous media. This research confirms that the influence of total absolute thermal conductivities of the fluid and rock on the effective thermal conductivity of the fluid-saturated porous medium diminishes after a certain local Nusselt number of the system. Finally, the result confirms that the convective ability of the fluid-saturated porous medium is apparently more pronounced than its conductive ability. This study will help to better understand the modeling of the EOR process thus improving process design and performance prediction.

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