Sandeep Hatte

Biography

Sandeep is a Ph.D. student in Mechanical Engineering department at Virginia Tech, specializing in the fluid flow and heat transfer characteristics of non-wetting surfaces. He obtained his B. Tech. degree in Mechanical Engineering from Indian Institute of Technology Jodhpur, India, in 2015. After that, he spent three years at Indian institute of Science, Bangalore, India, as a Junior Research Fellow where he worked on the interfacial fluid dynamics pertaining to the system of evaporating functional droplet(s). In 2018, he joined Advanced Materials and Technologies Laboratory as a Ph.D. student under the supervision of Prof. Ranga Pitchumani. Ever since, he has spent his time modeling the fluid flow and heat transfer characteristics of structured and multiscale rough non-wetting surfaces. His analysis promises prediction of improved drag reduction, enhanced convective and phase change (condensation) heat transfer on non-wetting surfaces.

Research

Analytical Model for Drag Reduction on Liquid-Infused Structured Non-Wetting Surfaces

Liquid-infused structured non-wetting surfaces provide alternating no-slip and partial slip boundary conditions to the fluid flow, resulting in reduced friction at the interface. In this work, an analytical model is developed for the evaluation of effective slip and, in turn, friction factor and drag reduction on liquid-infused structured non-wetting surfaces. By considering the entire range of anisotropy and heterogeneity of the surface structures as well as the full range of partial slip offered by the infusion liquid, the present model eliminates empirical fitting or correlations that are inherent in previous studies. Based on the effective slip length, drag reduction and skin friction coefficient values for Newtonian flow between two infinite parallel plates and flow in round tubes are calculated. Extension of Moody charts for non-wetting surfaces and design maps of surface meso/micro/nano texturing for achieving desired drag reduction are developed for a broad range of engineering applications.  

Fractal Model for Drag Reduction on Multiscale Non-wetting Rough Surfaces

Rough surfaces in contact with a flow of fluid exhibit alternating no-slip and free shear boundary conditions at the solid–liquid and air–liquid interfaces, respectively, thereby potentially offering drag reduction benefits. The balance between the dynamic pressure in the flow and the restoring capillary pressure in the inter-asperity spaces determines the stability of the Cassie state of wettability and is a function of the relative extent of no-slip and free shear regions per unit surface area. In this work, using a fractal representation of rough surface topography, an analytical model is developed to quantify the stability of the Cassie state of wettability as well as drag reduction and the friction factor for laminar flow in a rectangular channel between nonwetting multiscale rough surfaces. A systematic study is conducted to quantify the effects of fractal parameters of the surfaces and the flow Reynolds number on drag reduction and the friction factor. The studies are used to develop friction factor curves extending the classical Moody diagram to hydrophobic and superhydrophobic surfaces. On the basis of the studies, regime maps are derived for estimating the extent of drag reduction offered by hydrophobic and superhydrophobic surfaces, revealing that superhydrophobic surfaces do not always offer the best drag reduction performance.

Analysis of Laminar Convective Heat Transfer Over Structured Non-Wetting Surfaces

Structured non-wetting surfaces provide alternating no-slip and partial slip boundary conditions to the fluid flow which, in turn, affects the convective heat transfer performance over the surfaces. In this paper, an analytical model is developed for the interfacial Nusselt number, the overall Nusselt number and a thermal hydraulic performance factor for fluid flow in a cylinder patterned with structured non-wetting surfaces, for the two cases of uniform wall heat flux and uniform wall temperature. In addition, by considering the stability of the Cassie state of wettability and its transition to the Wenzel state for flow over superhydrophobic surfaces, the present model overcomes certain limitations of the previously reported studies in the literature. Based on the analytical formulations and the stability constraints, the present paper provides optimum design maps for tailoring structured non-wetting surfaces for maximizing convective heat transfer and the combined thermal-hydraulic performance in applications. Use of the design maps on example cases is also discussed. It is shown that the use of structured non-wetting surfaces is most effective for low Reynolds numbers and/or small cylinder radius.Structured non-wetting surfaces provide alternating no-slip and partial slip boundary conditions to the fluid flow which, in turn, affects the convective heat transfer performance over the surfaces. In this paper, an analytical model is developed for the interfacial Nusselt number, the overall Nusselt number and a thermal hydraulic performance factor for fluid flow in a cylinder patterned with structured non-wetting surfaces, for the two cases of uniform wall heat flux and uniform wall temperature. In addition, by considering the stability of the Cassie state of wettability and its transition to the Wenzel state for flow over superhydrophobic surfaces, the present model overcomes certain limitations of the previously reported studies in the literature. Based on the analytical formulations and the stability constraints, the present paper provides optimum design maps for tailoring structured non-wetting surfaces for maximizing convective heat transfer and the combined thermal-hydraulic performance in applications. Use of the design maps on example cases is also discussed. It is shown that the use of structured non-wetting surfaces is most effective for low Reynolds numbers and/or small cylinder radius.

Fractal Model for Convective Heat Transfer over Multiscale Rough Non-wetting Surfaces

Convective heat transfer in fluid flows over multiscale rough non-wetting surfaces is of interest in many applications. This article utilizes a fractal description of rough surface topographies to develop an analytical model for the evaluation of the interfacial Nusselt number, the overall Nusselt number and thermal hydraulic performance factor for fluid flow in a cylinder patterned with multiscale rough non-wetting surfaces, for the two cases of uniform wall heat flux and uniform wall temperature. In addition, for the case of air infused superhydrophobic surfaces, by considering the balance between the external dynamic pressure due to fluid flow and the restoring capillary pressure, an analytical model is developed to quantify the extent of partial wetting of the solid asperities. A systematic study is then conducted to quantify the effects of the fractal parameters of the rough surface, flow Reynolds number and cylinder radius on the convective heat transfer performance of the system. Based on the analytical formulations and the stability criteria, surface texture design maps are presented for maximizing the overall Nusselt number and the thermal hydraulic performance factor. Using the design maps it is shown that the use of rough non-wetting surfaces is most effective in the range of lower Reynolds number and small cylinder radius that offers the best convective heat transfer and thermal-hydraulic performance.

Publications

1. S. Hatte, K. Kant and R. Pitchumani, “Freezing Characteristics of a Water Droplet on a Multiscale Superhydrophobic Surface,” Langmuir, 39(33), 11898–11909, 2023.
2. S. Hatte, R. Stoddard and R. Pitchumani, “Novel Solid-Infused Durable Nonwetting Surfaces for Sustained Condensation Heat Transfer Enhancement,” Applied Thermal Engineering, 219, 119458, 2023.
3. S. Hatte and R. Pitchumani, “Effects of Temperature on Flow Fouling of Smooth and Nonwetting Surfaces,” Industrial & Engineering Chemistry Research, 61(38), 14355–14363, 2022.
4. S. Hatte and R. Pitchumani, “Novel Nonwetting Solid-Infused Surfaces for Superior Fouling Mitigation,” Journal of Colloid and Interface Science, 627, 308–319, 2022.
5. S. Hatte and R. Pitchumani, “Analysis of Silica Fouling on Nonwetting Surfaces,” Soft Matter, 18, 3403-3411, 2022.
6. S. Hatte, R. Stoddard and R. Pitchumani, “Generalized Analysis of Dynamic Flow Fouling on Heat Transfer Surfaces,” International Journal of Heat and Mass Transfer, 188, 122573, 2022.
7. S. Hatte and R. Pitchumani, “Analysis of Convection Heat Transfer on Multiscale Rough Superhydrophobic and Liquid Infused Surfaces," Chemical Engineering Journal, 424, 130256, 2021.
   
8. S. Hatte and R. Pitchumani, “Analytical Model for Drag Reduction on Liquid-Infused Structured Non-Wetting Surfaces,” Soft Matter, 17, 1388–1403, 2021. 
9. S. Hatte and R. Pitchumani, “Analysis of Laminar Convective Heat Transfer Over Structured Non-Wetting Surfaces,” International Journal of Heat and Mass Transfer, 167, 120810, 2021.
10. S. Hatte and R. Pitchumani, “Fractal Model for Laminar Drag Reduction on Multiscale Liquid Infused Rough Surfaces,” Langmuir, 36(47), 14386–14402, 2020.
11. S. Hatte, K. Nithyanandam and R. Pitchumani, “Quantification of Laminar Drag Reduction on Liquid-Infused Structured Non-Wetting Surfaces,” Paper Q23.00007, 72nd Annual Meeting of the APS Division of Fluid Dynamics, Seattle, Washington, November 2019.

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