Motion dynamics of a water drop located on a hydrophobic inclined surface under uniform airflow


Department of Mechanical Engineering, Shahrekord University, Shahrekord, Iran


Drop motion on a solid surface has many applications in science and engineering, such as in architecture, offshore structures, and electronics. The present paper aims to simulate the motion of a water droplet located on a hydrophobic inclined surface and investigate its deformation rate using ANSYS FLUENT software. The sessile droplet subjected to uniform airflow can be shed depending on the value of drag and drop’s adhesion forces. In the present work, coupled level set and volume of fluid method are employed to estimate the motion of the interface. The effect of drop size, wind velocity, drop contact angle, and drop size on the location, velocity, and drop deformation is investigated. The results demonstrate that the drop is splashed as the contact angle decreases. The drop acceleration has an approximately constant trend at Reynolds numbers ranging from 8000 to 80,000. The maximum acceleration corresponds to the hydrophilic surface and is equal to 0.9 m/s2. As the contact angle increases, the acceleration becomes constant. For instance, the drop acceleration is about -0.3 for a contact angle of 135°. The results reveal that the drop requires a longer time to reach the lowest point of the inclined surface by decreasing its diameter and increasing surface hydrophobicity and wind velocity. It is found that as surface hydrophobicity increases, the drop reaches the bottom of the surface in a long time in comparison with the deformed drop.


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