University of Twente Student Theses


Transport over a bubble mattress : the influence of interface geometry on effective slip and mass transport

Haase, A.S. (2012) Transport over a bubble mattress : the influence of interface geometry on effective slip and mass transport.

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Abstract:Interfacial gas/liquid transport can be improved by employing superhydrophobic surfaces. The gas entrapped in the micro-structures of such surfaces make these substrates slippery, thereby reducing the resistance towards fluid flow. The amount of effective wall slip depends on the microscopic geometry of the gas/liquid interface. A non-zero liquid velocity at the wall is not only beneficial for increasing momentum transport, but also for enhancing interfacial mass transport. In this study, the influence of the bubble mattress interface geometry on both momentum and mass transport is investigated by quantification of the effective slip length and the mass transfer enhancement. A bubble mattress is a superhydrophobic surface containing bubbles that are positioned transversely to the flow direction. Experiments utilising micro-particle image velocimetry demonstrate the strong dependency of effective wall slip on both bubble protrusion angle and surface porosity for liquid flow over a bubble mattress. This dependency is confirmed by numerical predictions and is in agreement with previously published analytical and numerical results. Simulations reveal that solute transport across slippery interfaces can be significantly enhanced compared to non-slippery interfaces as a result of the non-zero liquid wall velocity. Mass transfer enhancements up to 25% can be achieved.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics, 58 process technology
Programme:Chemical Engineering MSc (60437)
Awards:Finalist Shell Master Prize 2012
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