Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel
Microfluidic applications based on thermocapillary effects have recently gained considerable attention due to the transport phenomena driven by the dominant surface tension forces. Furthermore, two-layer fluids, used in various applications, e.g., biomedical engineering, microfluidics, and chemical...
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2025-02-01
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| Series: | Case Studies in Thermal Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214157X24017350 |
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| author | Radi A. Alsulami Kanchathan Wasuwatthanakul Kannan Premnath Mutabe Aljaghtham Saad Adam |
| author_facet | Radi A. Alsulami Kanchathan Wasuwatthanakul Kannan Premnath Mutabe Aljaghtham Saad Adam |
| author_sort | Radi A. Alsulami |
| collection | DOAJ |
| description | Microfluidic applications based on thermocapillary effects have recently gained considerable attention due to the transport phenomena driven by the dominant surface tension forces. Furthermore, two-layer fluids, used in various applications, e.g., biomedical engineering, microfluidics, and chemical processing, enhance flow dynamics control by manipulating flow mixing and characteristics. Since prior works did not consider slip effects, this work addresses this phenomenon by investigating the thermocapillary-driven convection in two superimposed fluids in a microchannel while simulating the behavior of superhydrophobic surfaces. This is achieved by deriving a new analytical solution for thermocapillary convection between two solid walls, uniquely subject to the Navier slip condition and where the bottom surface is heated nonuniformly via a sinusoidal variation, under the limit of zero Reynolds and Marangoni numbers. The derived expressions for the flow field arising from the prevailing surface tension gradient are then explicitly parameterized by a dimensionless slip coefficient obtained by combining the Navier slip length and the wavenumber of the imposed temperature variation on the bottom surface, along with the ratios of the properties of fluids and their thicknesses. We study the effect of the various characteristic parameters on the thermocapillary flow patterns and the maximum interfacial velocity currents. In particular, it is shown that thermo-capillarity generates convective currents with nominally a pair of counter-rotating vortices in each fluid, which is sometimes increased and accompanied by a change in their sense of rotation and the magnitude of the peak velocities by variations in the dimensionless slip coefficient. These results elucidate the role of the competing effects of the wall shear variations due to slip and the thermocapillary motions in the bulk regions facilitated by the viscous forces, which can be exploited in modulating mixing and transport in microchannels. |
| format | Article |
| id | doaj-art-77ceaf8953de4cbaac19f89c21feb478 |
| institution | Kabale University |
| issn | 2214-157X |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Thermal Engineering |
| spelling | doaj-art-77ceaf8953de4cbaac19f89c21feb4782025-02-02T05:27:12ZengElsevierCase Studies in Thermal Engineering2214-157X2025-02-0166105704Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannelRadi A. Alsulami0Kanchathan Wasuwatthanakul1Kannan Premnath2Mutabe Aljaghtham3Saad Adam4Department of Mechanical Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah, 21589, Saudi Arabia; Corresponding author. Department of Mechanical Engineering, King Abdulaziz University, Room No. 24E36, Building No. 40, Faculty of Engineering, P.O. Box 80204, Jeddah, 21589, Saudi Arabia.Department of Mechanical Engineering, College of Engineering, Design and Computing, University of Colorado Denver, Denver, CO, 80217, USADepartment of Mechanical Engineering, College of Engineering, Design and Computing, University of Colorado Denver, Denver, CO, 80217, USADepartment of Mechanical Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Al Kharj, 16273, Saudi ArabiaDepartment of Mechanical Engineering, University of Tobruk, Tobruk, LibyaMicrofluidic applications based on thermocapillary effects have recently gained considerable attention due to the transport phenomena driven by the dominant surface tension forces. Furthermore, two-layer fluids, used in various applications, e.g., biomedical engineering, microfluidics, and chemical processing, enhance flow dynamics control by manipulating flow mixing and characteristics. Since prior works did not consider slip effects, this work addresses this phenomenon by investigating the thermocapillary-driven convection in two superimposed fluids in a microchannel while simulating the behavior of superhydrophobic surfaces. This is achieved by deriving a new analytical solution for thermocapillary convection between two solid walls, uniquely subject to the Navier slip condition and where the bottom surface is heated nonuniformly via a sinusoidal variation, under the limit of zero Reynolds and Marangoni numbers. The derived expressions for the flow field arising from the prevailing surface tension gradient are then explicitly parameterized by a dimensionless slip coefficient obtained by combining the Navier slip length and the wavenumber of the imposed temperature variation on the bottom surface, along with the ratios of the properties of fluids and their thicknesses. We study the effect of the various characteristic parameters on the thermocapillary flow patterns and the maximum interfacial velocity currents. In particular, it is shown that thermo-capillarity generates convective currents with nominally a pair of counter-rotating vortices in each fluid, which is sometimes increased and accompanied by a change in their sense of rotation and the magnitude of the peak velocities by variations in the dimensionless slip coefficient. These results elucidate the role of the competing effects of the wall shear variations due to slip and the thermocapillary motions in the bulk regions facilitated by the viscous forces, which can be exploited in modulating mixing and transport in microchannels.http://www.sciencedirect.com/science/article/pii/S2214157X24017350Thermocapillary convectionNavier slip conditionMarangoni stressMicrochannelSuperhydrophobic surfacesAnalytical solutions |
| spellingShingle | Radi A. Alsulami Kanchathan Wasuwatthanakul Kannan Premnath Mutabe Aljaghtham Saad Adam Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel Case Studies in Thermal Engineering Thermocapillary convection Navier slip condition Marangoni stress Microchannel Superhydrophobic surfaces Analytical solutions |
| title | Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| title_full | Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| title_fullStr | Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| title_full_unstemmed | Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| title_short | Thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| title_sort | thermocapillary convection in superimposed fluids confined within superhydrophobic surfaces of a microchannel |
| topic | Thermocapillary convection Navier slip condition Marangoni stress Microchannel Superhydrophobic surfaces Analytical solutions |
| url | http://www.sciencedirect.com/science/article/pii/S2214157X24017350 |
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