scholarly journals The Instability of an Electrohydrodynamic Viscous Liquid Micro-Cylinder Buried in a Porous Medium: Effect of Thermosolutal Marangoni Convection

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Galal M. Moatimid ◽  
Mohamed A. Hassan

The electrohydrodynamic (EHD) thermosolutal Marangoni convection of viscous liquid, in the presence of an axial electric field through a micro cylindrical porous flow, is considered. It is assumed that the surface tension varies linearly with both temperature and concentration. The instability of the interface is investigated for the free surface of the fluid. The expression of the free surface function is derived taking into account the independence of the surface tension of the heat and mass transfer. The transcendental dispersion relation is obtained considering the dependence of the surface tension on the heat and mass transfer. Numerical estimations for the roots of the transcendental dispersion relation are obtained indicating the relation between the disturbance growth rate and the variation of the wave number. It is found that increasing both the temperature and concentration at the axial microcylinder has a destabilizing effect on the interface, according to the reduction of the surface tension. The existence of the porous structure restricts the flow and hence has a stabilizing effect. Also, the axial electric field has a stabilizing effect. Some of previous analytical and experimental results are recovered upon appropriate data choices.

2005 ◽  
Vol 128 (6) ◽  
pp. 520-529 ◽  
Author(s):  
Y. Huo ◽  
B. Q. Li

A numerical study is presented of the free surface deformation and Marangoni convection in immiscible droplets positioned by an electrostatic field and heated by laser beams under microgravity. The boundary element and the weighted residuals methods are applied to iteratively solve for the electric field distribution and for the unknown free surface shapes, while the Galerkin finite element method for the thermal and fluid flow field in both the transient and steady states. Results show that the inner interface demarking the two immiscible fluids in an electrically conducting droplet maintains its sphericity in microgravity. The free surface of the droplet, however, deforms into an oval shape in an electric field, owing to the pulling action of the normal component of the Maxwell stress. The thermal and fluid flow distributions are rather complex in an immiscible droplet, with conduction being the main mechanism for the thermal transport. The non-uniform temperature along the free surface induces the flow in the outer layer, whereas the competition between the interfacial surface tension gradient and the inertia force in the outer layer is responsible for the flows in the inner core and near the immiscible interface. As the droplet cools into an undercooled state, surface radiation causes a reversal of the surface temperature gradients along the free surface, which in turn reverses the surface tension driven flow in the outer layer. The flow near the interfacial region, on the other hand, is driven by a complimentary mechanism between the interfacial and the inertia forces during the time when the thermal gradient on the free surface has been reversed while that on the interface has not yet. After the completion of the interfacial thermal gradient reversal, however, the interfacial flows are largely driven by the inertia forces of the outer layer fluid.


2021 ◽  
Author(s):  
Bahshillo Akramov ◽  
◽  
Sherali Umedov ◽  
Odiljon Khaitov ◽  
Jaloliddin Nuriddinov ◽  
...  

The work is devoted to increasing the degree of depletion of reserves of longterm exploited hydrocarbon deposits on the basis of the obtained results of theoretical and experimental studies of the application of electrodynamic technologies for stimulating the formation and bottomhole formation zone. The electrolysis of formation fluids, water, oil-bearing rocks, is accompanied by a mass transfer, primary and secondary chemical reactions, the formation of all kinds of salts, alkalis and acids, new organic substances and all kinds of surfactants. Not only the liquid is subjected to electrolysis, but also the oil and gas bearing rocks themselves (solid electrolyte). The magnetic and electrical forces arising during the electric treatment of reservoirs make it possible to effectively drain heterogeneous reservoirs and extract residual oil from non-working layers. The work also carried out experiments to study the effect of the electric field on the surface tension coefficient at the oil-water interface. The circumstance of an abrupt change in the surface tension coefficient at the oil-water interface makes it possible in principle to create conditions in the reservoir that make it possible to slow down the cusping processes by applying an electric field of various magnitudes or, in other words, by regulating the amount of mass transfer. In numerical terms, the oil recovery factor without electrophysical treatment was 52.94%. Under electrophysical impact, the oil recovery factor was 94.12%, i.e. equaled to almost complete extraction of oil from the sample. In the field, this figure, of course, will decrease by 2-3 times, but it remains quite high in comparison with other methods of increasing oil recovery. Thus, the studies performed on samples in laboratory conditions indicate the possibility of using constant electric fields to increase oil recovery from depleted watered formations. Electrochemical treatment of the formation can significantly increase the displacement of oil from the formation. The increase in oil displacement reaches 15-20% and more. With the help of water alone, 58% of the oil (of its total volume in the sand) was displaced from the sand, and under electric field with a voltage of 10 V and 20 V, the total amount of displaced oil, respectively, increased to 67 and 83%. Thus, the laboratory studies performed on the samples also indicate the possibility of using constant electric fields to increase oil recovery from depleted watered formations. The carried out theoretical and experimental studies show the possibility of using the technology of electrochemical and electrothermochemical leaching of oilsaturated rocks to intensify oil production. The effectiveness of the recommended technology is especially noticeable in fields that have entered the final stage of development with a high water cut.


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