Flow near the contact line of an evaporating droplet

Bloemen, Oscar (2012) Flow near the contact line of an evaporating droplet.

Abstract:Evaporating droplets with small contact angles posses an evaporative flux that is singular at the contact line. It has been argumented that near the contact line this singularity gives such a powerful outflow, that the flow must be normal to the surface of the droplet. A flow field with this property prohibits application of the lubrication theory near the contact line of the droplet. In this work the flow field near the contact line is solved analytically for an arbitrary contact angle. From this solution we demonstrate that the lubrication approximation does accurately describe the flow field near the contact line, which is in agreement with experiments.The analytical solution of the flow field near the contact line also gives the opportunity to observe the flow for larger contact angles. Remarkably, for these contact angles, regions are found where the flow is in the opposite direction as one might expect. To investigate these regions in the whole droplet, numerical simulations are performed. The simulations con�rm existence of these regions near the contact line, away from the contact line we see that these regions correspond to a flow circulation in the droplet.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics MSc (60436)
Link to this item:http://purl.utwente.nl/essays/63430
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