Abstract
Motivated by the need for practical, high fidelity, simulation of water over surface features of road vehicles a Coupled Level Set Volume of Fluid (CLSVOF) method has been implemented into a general purpose CFD code. It has been implemented such that it can be used with unstructured and non-orthogonal meshes. The interface reconstruction step needed for CLSVOF has been implemented using an iterative ‘clipping and capping’ algorithm for arbitrary cell shapes and a re-initialisation algorithm suitable for unstructured meshes is also presented. Successful verification tests of interface capturing on orthogonal and tetrahedral meshes are presented. Two macroscopic contact angle models have been implemented and the method is seen to give very good agreement with experimental data for a droplet impinging on a flat plate for both orthogonal and non-orthogonal meshes. Finally the flow of a droplet over a round edged channel is simulated in order to demonstrate the ability of the method developed to simulate surface flows over the sort of curved geometry that makes the use of a non-orthogonal grid desirable.
Highlights
There are several engineering applications which involve the flow of liquid droplets or rivulets over solid surfaces
In this paper we present a method based on the Coupled Level-Set Volume of Fluid (CLSVOF) implemented such that it can be used in non-orthogonal or unstructured meshes
That the accuracy of the method has been demonstrated, subject to an accurate contact angle model, we present results to demonstrate the ability of the Coupled Level Set Volume of Fluid (CLSVOF) method to simulate free surface flow over curved geometry
Summary
There are several engineering applications which involve the flow of liquid droplets or rivulets over solid surfaces One such application is ‘Exterior Water Management’ (EWM) on road vehicles. Examples of EWM simulations can be found in Gaylard et al (2012) and Jilesen et al (2015) that both use Lagrangian particle tracking for the airborne droplets and a 2D film model for the surface flow. Dianat et al / International Journal of Multiphase Flow 91 (2017) 19–38 film is stripped off the surface it breaks down immediately into a spray of droplets small in comparison to the computational mesh This model would not give correct results in cases where the liquid leaves the surface in a coherent mass. The method must include the different behaviour of water on different surfaces such as paintwork, glass or treated hydrophobic surfaces
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