Coupled Level Set Volume Of Fluid Research Articles

Numerical study on the gas-liquid interface in the hydrogen reduction of copper slag process

Hydrogen reduction provides an environmentally friendly alternative to traditional smelting for copper slag. The study investigates the gas–liquid interface dynamics during the process. A numerical model based on Coupled Level Set-Volume of Fluid (CLSVOF) and Large Eddy Simulation (LES) methods has been developed and validated against experimental data. The model accurately depicts bubbling modes and interface characteristics in the reactor. Results indicate periodic self-similar patterns in interfacial area and gas volume signals. The vorticity distribution shows asymmetry and swirling patterns, with higher vorticity in the gas injection and upper liquid surface regions. The mass transfer efficiency is higher in the bubble plume region than in the upper surface. Increasing gas flow rates expands the gas–liquid interface areas but decreases mass transfer efficiency in the bubble plume while increasing it in the upper surface. These findings provide valuable insights into the efficiency of the hydrogen reduction of the copper slag process.

Computational investigation of vertical upflow boiling of liquid nitrogen and effects of bubble collision dispersion force

The present study investigates the performance of 2-D axisymmetric computational fluid dynamics (CFD) in predicting boiling characteristics of liquid nitrogen flowing vertically upwards along a uniformly heated circular tube. Investigation of the popular Volume of Fluid (VOF) model reveals (a) inaccurate surface tension calculation which degrades interface tracking, and (b) under-representation of bubble-to-bubble interaction, which stems from the innate nature of employing a single momentum equation in VOF. To alleviate VOF shortcomings, Coupled Level Set VOF (CLSVOF) is adopted in ANSYS FLUENT, including a user defined function to account for the crucial effects of bubble collision dispersion force. The CFD simulation results are validated against wall temperature and volume fraction results from prior benchmark experiments corresponding to four different wall heat flux conditions at nearly identical mass velocities. Predictions are also provided for axial variations of interfacial flow pattern, fluid temperature, and fluid velocity, flow characteristics that are very difficult to measure in cryogenic experiments. The CFD simulation results are shown to be highly accurate at predicting the nucleate boiling portion of the flow boiling curve.

Investigations of interfacial heat transfer and phase change on bioinspired superhydrophobic surface for anti-icing/de-icing

The bioinspired superhydrophobic surface (SHS) demonstrates the capability in terms of anti-icing/de-icing, however, the mechanisms of micro−/nanostructure on interfacial heat transfer and phase change are inadequately revealed during freezing. A comprehensive solution method, considers a modified roughness, texture, and thermal properties of SHSs material, is developed in this study. This method, coupled Level Set-Volume of Fluid (CLSVOF) with solidification model and combined freezing experiments, captures the ice-liquid-gas interface change and anisotropic interfacial heat exchange. Numerical and experimental results in frozen nucleation illustrate that the micro−/nanostructure blocks heterogeneous heat transfer via the stored air, extended the freezing time and the freezing delay rate is 194%. Accordingly, the numerical model between freezing time (t) and surface temperature (Tsurface), is following power function t = 959.42 × (273.15 − Tsurface)−0.777. Moreover, the moving droplets overcome the freezing adhesion through shortening the contact time then to limit the heat exchange process, allowing their self-removal before freezing. The de-icing analysis confirms that the larger contact angle (CA) and cavitation structure jointly affect the solid-liquid contact area, and the bionic surface in this study reduces the adhesion strength of frozen droplets by 4 times.

Numerical simulation of single/double liquid jets in supersonic crossflows

This study investigates the mixing processes of liquid jets in supersonic crossflows at a Mach number of 2.1 by using numerical simulations that employ the Coupled Level-Set/Volume-of-Fluid (CLSVOF) method, which is based on the Delayed Detached Eddy Simulation (DDES). The instantaneous spray morphology from the simulations agreed well with the experimental data. The spray presents the ‘Ω’ shape when viewed from the front, and the maximum error in the penetration depth was 15% from a side perspective. The direction of the air movement determined the shape of the liquid column shearing and breaking. In turn, the breaking process of the liquid jet significantly affects the structure of the air flow. Three-dimensional flow around the liquid column occurred when the supersonic incoming flow impinged on the liquid column, ultimately forming counter-rotating vortex pairs (CVP) in the inner region of the spray. Evolution of the reverse vortex pair accelerated the mixing process of the spray. Single liquid jet was used as a basis to further study double jets in Mach 2.1 airflow. The results show that the breaking length and penetration depth of the downstream jet are significantly improved.

A hybrid moment of fluid–level set framework for simulating primary atomization

This paper presents a hybrid moment of fluid–level set (HyMOFLS) method of liquid/gas interface reconstruction for the application to simulate primary atomization of liquid fuel. This method combines the moment of fluid (MOF) method and the level set framework in the coupled level set volume of fluid (CLSVOF) method. In this hybrid method, the MOF and CLSVOF methods are used to reconstruct the interface in the under-resolved and the resolved regions of the flow, respectively. An interface surface resolution metric called interface resolution quality (IRQ) is introduced to identify and classify these two flow regions in the computational domain. Such a strategy classifies/tags each computational cell with MOF or CLSVOF method based on a threshold value for the IRQ. The MOF method uses liquid volume fraction as well as centroids of liquid and gas phases for the interface reconstruction. The CLSVOF method uses the level set for describing the interface and liquid volume fraction for conserving the mass. The phase centroids in the HyMOFLS method are computed and transported on-the-fly during the cell tagging process. The transport of the liquid volume fraction, level set, and the phase centroids are performed using a directionally split algorithm. This algorithm is coupled with the Navier-Stokes equations solver that uses ghost fluid method as well as consistent mass and momentum flux computation for the momentum equation. Various numerical tests that exhaustively assess the capabilities, accuracy, and computational time consumption of the HyMOFLS method under multiple flow conditions and configurations are presented. The results from these tests suggest that this hybrid framework is capable of well capturing the liquid/gas interface belonging to thin and under-resolved structures that are often encountered in simulations of turbulent atomization of liquids. Following these tests, a detailed parametric study on the threshold value of IRQ is presented to test its effect on the accuracy of interface reconstruction. Finally, this hybrid framework is employed to simulate turbulent jet injection and pre-filming planar Airblast atomization cases of engineering applications. The proposed HyMOFLS method is found to achieve a good balance between the accuracy and the computational cost of reconstructing the liquid/gas interface for complex and turbulent atomization configurations.

Direct numerical simulation of turbulent bubbly down flow using an efficient CLSVOF method

We use direct numerical simulations (DNS) to investigate the turbulent modulation due to the presence of bubbles in vertical channels flowing downward. The Reynolds number for single-phase flow based on half channel height h* and friction velocity is Reτ= 180. A density and viscosity ratio of ρd*/ρc*=0.01 and μd*/μc*=0.018 is chosen for two void fractions of ϵ=1.2% and ϵ=2.4%. For each void fraction three different bubble sizes are simulated: D/h=0.2130, 0.2684 and 0.3382, where D denotes the diameter of the bubbles. Numerical simulations are based on multiple markers Coupled Level-Set/Volume-of-Fluid (CLSVOF) method. To improve the efficiency of this method, a fast pressure-correction method is used in order to enable the simulation to exploit a constant coefficient Poisson equation which can be solved with FFT-based technique. Extensive verification and validation were performed and perfect accuracy and agreement are obtained. In all the simulations performed in this work, the new Poisson solver showed a minimum speedup of 22 times.Accumulation of bubbles in the core region of the channel for all cases is observed, which forms a bubble-free layer in the near-wall region. The presence of bubbles resulted in considerable modification in the mean velocity profile compared to single-phase flow. Another common observation is that all the components of velocity fluctuations in the near-wall region decrease with increasing void fraction and decreasing wall layer thickness. The opposite happens in the core region, where the presence of bubbles favours turbulence. With respect to the bubble size, the wall-normal and spanwise velocity fluctuations decrease in the near-wall region for smaller bubbles, however, the streamwise velocity fluctuations remained almost unaffected. The investigation of turbulent kinetic budgets shows that, unlike single-phase flow, the dissipation terms rises to large values in the core region of the channel. This behaviour is referred to the presence of bubbles and hence enhancement of turbulent kinetic energy in the core region.

Analysis of Oil-Air Two-Phase Flow Characteristics inside a Ball Bearing with Under-Race Lubrication

Under-race lubrication can increase the amount of lubricating oil entering a bearing and greatly improve lubrication and cooling effects. The oil-air two-phase flow characteristics inside a ball bearing with under-race lubrication play a key role in lubrication and cooling performance. The motions of ball bearing subassemblies are complicated. Ball spin affects the oil volume fraction. In this paper, the coupled level set volume of fluid (CLSVOF) method is used to track the oil-air two-phase flow inside the ball bearing with under-race lubrication. The influence of various factors on the oil volume fraction inside the ball bearing with under-race lubrication is investigated, particularly rotating speeds, inlet velocity and the size of oil supply apertures under the inner ring. The influence of the ball spinning is analyzed separately. The result demonstrates that, on account of the centrifugal force, lubricating oil is located more on the outer ring raceway at rotational speeds of 5000 r/min, 10,000 r/min, 15,000 r/min and 20,000 r/min. The oil volume fraction inside the bearing gradually increases at an oil inlet velocity of 5 m/s, 10 m/s and 15 m/s. The circumferential distribution of oil is also similar. As the diameter of the oil supply aperture increases from 1.5 mm to 2 mm, the oil volume fraction increases inside the ball bearing. However, the oil volume fraction slightly decreases from 2 mm to 2.5 mm of oil supply aperture diameter. Ball spin does not affect the circumferential distribution trend of the lubricating oil, but slightly reduces the oil volume fraction. Furthermore, ball spin causes the surface fluid to rotate around its rotation axis and increases the speed.

DNS and LES of primary atomization of turbulent liquid jet injection into a gaseous crossflow environment

In this paper, we study the primary atomization characteristics of liquid jet injected into a gaseous crossflow through direct numerical simulations (DNS) and large eddy simulations (LES). The DNS use a coupled level set volume of fluid (CLSVOF) sharp interface capturing method resolving all relevant scales to predict the drop size distribution (DSD) for drops larger than the grid spacing. The LES use a volume of fluid (VOF) diffused interface method modelling the sub grid droplets. The purpose of this paper is to provide a comparison of the results of drop data between DNS and LES. The simulations are performed for a liquid jet injection with liquid-gas momentum flux ratio of 6.6, liquid jet Reynolds number of 14,000 injected into a crossflowing air with Reynolds number 570,000 and Weber number of 330 at a liquid-to-gas density ratio of 10. Two distinct and simultaneous atomization/breakup mechanisms have been observed in the simulations: column/bag breakup and ligament/surface breakup. It was found that the DSDs obtained from the DNS and LES each follow a log-normal distribution based on their respective droplet diameter data. An overlap region exists between the individual DSDs from the DNS and LES when combined. The width of this overlap region decreases along the downstream direction. A log-normal distribution is found to be a good fit to the combined DSD incorporating both resolved and sub-grid droplets. This information is relevant for the secondary atomization simulations and modeling.

Investigation of Wave Stripping Models on a Generic Wing-Mirror Using a Coupled Level-Set Volume of Fluid Simulation

<div class="section abstract"><div class="htmlview paragraph">Predicting Exterior Water Management is important for developing vehicles that meet customer expectations in adverse weather. Fluid film methods, with Lagrangian tracking, can provide spray and surface water simulations for complex vehicle geometries in on-road conditions. To cope with this complexity and provide practical engineering simulations, such methods rely on empirical sub-models to predict phenomena such as the film stripping from the surface. Experimental data to develop and validate such models is difficult to obtain therefore here a high-fidelity Coupled Level-set Volume of Fluid (CLSVOF) simulation is carried out. CLSVOF resolves the interface of the liquid in three dimensions; allowing direct simulation of film behaviour and interaction with the surrounding air. This is used to simulate a simplified wing-mirror, with air flow, on which water is introduced. The film shows very different behaviour on the in-board section, where a film is developed which eventually breaks to rivulets, and the end of the mirror, where the water is rapidly stripped off the surface due to the higher shear stress from the air. The same case is simulated using a fluid film method, which shows that a simple film stripping model based on film height is not capable of predicting the different regimes observed with CLSVOF. However, a model based on wave stripping due to Kelvin-Helmholtz instability is seen to give good agreement, as was a model based on local film velocity, surface curvature and body force. As well as informing the development of a film stripping model, this also illustrates how a high-fidelity simulation can be used as a tool for developing practical engineering software.</div></div>

Three-dimensional flow breakup characteristics of a circular jet with different nozzle geometries

The Reynolds-averaged Navier–Stokes (RANS), large eddy simulation (LES), and coupled level set-volume of fluid (CLSVOF) methods were used to numerically investigate the breakup characteristics of three-dimensional unsteady circular jets. The jet breakup lengths and initial amplitudes of the surface waves of the jets from nozzles with different geometries were measured in a high-speed photography (HSP) experiment. The numerical model showed the formation, development, and variation of the jet flow structure. The circumferential and sinusoidal waves on the jet surface were captured by a high-speed camera, and the entrainment effect of the jet was studied with LES. The time-averaged velocity distribution fields were clarified with LES; the breakup of the liquid band structure and formation of droplets led to irregular changes in the droplet velocities, which indicates that the LES of the jet breakup was close to the actual situation. The relative errors between the simulation and experimental values for the breakup length and initial amplitude of the surface waves of the jet were less than 10%, which confirms that LES and CLSVOF can accurately and feasibly extract the details of circular jet breakup characteristics under intermediate- and low-pressure conditions. • Breakup characteristics of 3D unsteady circular jets numerically simulated. • Different methods compared with jet breakup length and initial surface wave amplitude. • Large-eddy simulation method showed good agreement with experimental results. • Results can be used to characterise intermediate-pressure jets for irrigation systems.

Slag eye formation in single and dual bottom purged industrial steelmaking ladles

ABSTRACTArgon gas is often injected from the bottom of the ladle during steel refining operations. The injected gas interacts with the liquid (metal and slag) bath and enhances the momentum, heat, and mass transfer rate in the melt. However, during these gas–liquid interactions, an opening of the slag layer called slag eye is formed, which exposes the molten metal surface to the atmosphere, which is generally undesirable. In the current work, a transient, three-dimensional mathematical model is used to study the turbulent gas–liquid interactions in single as well as dual bottom blown industrial steelmaking ladles. A Coupled Level Set Volume of Fluid (CLSVOF) model is used for tracking the steel-argon, steel-slag, and argon-slag interfaces, from which the slag-eye area has been predicted. It is found that the inlet gas purging rate, melt height, slag layer thickness, angular and radial positions of the gas inlets affect the slag opening area. Non-dimensional empirical correlations are proposed to predict the slag opening area in both single as well as dual purged ladles, using non-linear regression analysis.

Computational and experimental analysis of droplet transportation/jetting behaviours driven by thin film surface acoustic waves

A Coupled Level Set Volume of Fluid (CLSVOF) approach has been applied to investigate severe deformation/transportation/jetting behaviours of sessile droplet driven by thin-film surface acoustic waves (SAW) devices. For validation of this computational method, a series of experimental studies of droplet transportation/jetting were performed using ZnO/Si thin film based SAW devices with resonant frequencies ranging from 64.49 MHz to 271.36 MHz. Good agreements between the computational and experimental results showed the capability of the developed CLSVOF method in modelling complex acoustofluidics phenomena such as significant internal streaming, pumping and jetting of the droplet driven by the propagating SAW.Results obtained from the computational model are used to clarify the fluidic mechanisms of droplet oscillation and wobbling behaviours during transportation. Numerical results reveal the liquid streaming patterns and airflow velocity field around the droplet at different stages of transportation/jetting process. Effects of droplet volume, the resonant frequency of SAW devices and applied SAW power on droplet transportation/jetting were investigated both theoretically and experimentally. In particular, comparisons between experimental and computational results showed that the model predicted well the minimum RF power to start droplet pumping and jetting at various resonant frequencies.

Research on dam-break flow induced front wave impacting a vertical wall based on the CLSVOF and level set methods

The problem of a dam-break flow induced front wave impacting a vertical wall placed at the downstream end was numerically investigated by using the Level Set (LS) method and Coupled Level Set/Volume Of Fluid (CLSVOF) method. For the LS approach, the advection equation of the level set function to capture the interface is discretized by the fifth-order, weighted, essentially non-oscillatory (WENO5) scheme. For the CLSVOF approach, the Tangent of Hyperbola for Interface Capturing/Weighed Line Interface Calculation (THINC/WLIC) scheme is adopted to capture the interface and improve mass conservation. The interface normal vector in the WLIC reconstruction procedure can be estimated from the LS function instead of VOF function. The Navier–Stokes solver which uses an explicit Adams–Bashforth algorithm is performed on a staggered Eulerian grid. The numerical experiments are carried out in a rectangular flume with a smooth horizontal wet bed with four different tailwater levels. This study investigates the formation and propagation of the negative wave resulting from the reflection of flood waves against the downstream end wall. The numerical results are compared with laboratory experiment results studied in Ref (Kocaman and Ozmen-Cagatay, 2015). and a reasonable agreement is achieved. Numerical results show that the CLSVOF solutions are better than LS solutions in terms of mass conservation.

Slip theory-based numerical investigation of the fluid transport behavior on a surface with a biomimetic microstructure

This paper presented a numerical simulation of drag reduction on a superhydrophobic surface with a groove structure. The computational fluid dynamics (CFD) method was used to analyze the effect of the groove microstructure when droplets impacted a superhydrophobic surface. The simulation results revealed three main characteristics: (1) The distance the droplet spread was larger along the direction parallel to the groove and smaller perpendicular to the groove; (2) Two protruding small spheres were formed at the edge of the droplet along the groove direction; (3) During retraction, the droplets presented a narrow, cross-shaped morphology. The effect of the groove structure in the two-dimensional microchannel on drag reduction near the wall was analyzed based on slip theory by the coupled level set/volume of fluid (CLSVOF) method. The air in the superhydrophobic pit formed a low-velocity vortex, which made the fluid roll on the air surface. The rolling on the surface produced a velocity slip at the gas–liquid interface. In addition, the superhydrophobic surface had an obvious drag reduction effect in the laminar flow state, but the drag reduction effect in the turbulent state was not ideal and even increased the flow resistance at the wall.

Pressure and Velocity Fluctuation in the Numerical Simulation of Bubble Detachment in a Venturi-Type Bubble Generator

The Venturi-type bubble generator proposed by Oak Ridge National Laboratory is used to produce micro-sized bubbles. In this paper, a numerical simulation is carried out to study the process of the bubble formation and detachment from a wall orifice of a Venturi-type bubble generator in a cross-flowing liquid. The Volume-of-Fluid (VOF) method is applied to track the two-phase interface and study the evolution of the bubble formation. The result of the computation provides a visual three-dimensional bubble and shows the process of bubble formation and detachment. Three stages are identified during bubble formation (the expansion stage, the rising stage, and the collapse stage). Because of the compressibility of the gas, a fluctuation of the pressure and the mass flow rate in the gas chamber is observed, which is considered a significant effect on the bubble formation and detachment. The mechanism of the bubble detachment is clarified with the help of the mass flow rate fluctuation. The equivalent diameter is compared with that predicted by a previous model. A Coupled Level Set Volume-of-Fluid (CLSVOF) simulation is compared with the VOF simulation; the three stages and the fluctuation are also observed in the CLSVOF simulation.

Experimental and Numerical Visualization of Heat Transfer and Hydrodynamics Induced by Double Droplet Train Impingement

The objective of this study was to visualize and simulate the thermal physical process during double droplet train impingement for three different horizontal impact spacings (S = 0.65 mm, 1.2 mm and 2 mm). Two identical HFE-7100 droplet trains were produced using a piezoelectric droplet generator at a frequency of 6000 Hz with a corresponding droplet Weber number of 312. A translucent sapphire substrate with a thin film ITO coating was used as heater in the experiments. The heat transfer and hydrodynamics of double droplet train impingement have been visualized using IR thermal imaging and high speed optical imaging techniques, respectively. The double droplet train impingement process was also simulated numerically using the Coupled Level Set-Volume of Fluid (CLS-VOF) approach with dynamic mesh adaption (DMA). Humps were observed both numerically and experimentally between two adjacent impact craters due to the interactions caused by the impinging droplet trains. It was found that the hump height decreased when impact spacing increased. IR images show that higher impact spacing leads to better heat transfer performance, which could be due to the lower hump height at greater impact spacing conditions. It was also observed that higher impact spacing leads to better thermo-hydrodynamics within and outside the impingement zone. In summary, results show that horizontal impact spacing plays a significant role in double droplet train impingement cooling. This work was supported by the National Priority Research Program of the Qatar National Research Fund, Grant No.: NPRP 6-1304-2-525.

A pressure based method for vaporizing compressible two-phase flows with interface capturing approach

This study focuses on the development of a pressure based method able to capture compressibility effects and phase change in turbulent two-phase flow DNS, using the Coupled Level Set/Volume of Fluid (CLSVOF) interface capturing method. A compressible VOF equation and a new pressure equation are described, including additional terms due to vaporization and compressibility. First, validation cases without phase change such as a gas-water shock tube and an oscillating water column configuration have been performed. Concerning the first case, obtained results suggests that the method is able to capture accurately the shock wave characteristics. For the second case, a reference solution is computed and compared with DNS results, showing the method accuracy and convergence.Finally, a two-phase Homogeneous Isotropic Turbulence with compressibility and phase change is investigated. Contrary to previous works, the vaporization process has an impact on the flows dynamics. The effects of the vaporization on the gas density is illustrated and compared with a reference solution for a constant vaporization rate. Great agreement is obtained between DNS results and the reference solution. The mass balance between total mass, gas and liquid mass is also shown and demonstrates the efficiency of the CLSVOF interface capturing method regarding mass conservation, even in a turbulent atomization context.

An iterative interface reconstruction method for PLIC in general convex grids as part of a Coupled Level Set Volume of Fluid solver

Reconstructing the interface within a cell, based on volume fraction and normal direction, is a key part of multiphase flow solvers which make use of piecewise linear interface calculation (PLIC) such as the Coupled Level Set Volume of Fluid (CLSVOF) method. In this paper, we present an iterative method for interface reconstruction (IR) in general convex cells based on tetrahedral decomposition. By splitting the cell into tetrahedra prior to IR the volume of the truncated polyhedron can be calculated much more rapidly than using existing clipping and capping methods. In addition the root finding algorithm is designed to take advantage of the nature of the relationship between volume fraction and interface position by using a combination of Newton's and Muller's methods. In stand-alone tests of the IR algorithm on single cells with up to 20 vertices the proposed method was found to be 2 times faster than an implementation of an existing analytical method, while being easy to implement. It was also found to be 3.4–11.8 times faster than existing iterative methods using clipping and capping and combined with Brent's root finding method. Tests were then carried out of the IR method as part of a CLSVOF solver. For a sphere deformed by a prescribed velocity field the proposed method was found to be up to 33% faster than existing iterative methods. For simulations including the solution of the velocity field the maximum speed up was found to be approximately 52% for a case where 12% of cells lie on the interface. Analysis of the full simulation CPU time budget also indicates that while the proposed method has produced a considerable speed-up, further gains due to increasing the efficiency of the IR method are likely to be small as the IR step now represents only a small proportion of the run time.

Comparison of the Volume of Fluid and CLSVOF Methods for the Assessment of Flow Boiling in Silicon Microgaps

The three-dimensional (3D) stacking of integrated circuits (ICs), and emergent microelectronic technologies require low-profile cooling solutions for the removal of relatively high heat fluxes. The flow boiling of dielectric refrigerants represents a feasible alternative to such applications by providing compatibility with the electrical interconnections, relatively uniform temperature profiles, and higher heat transfer coefficients than those obtained with single phase-cooling. Despite important experimental evidence in this area has been recently reported in the literature, the modeling of such has remained in basic and limited forms due to the associated complexities with the physics of two-phase flow with phase-change. In an effort to expand the studied possibilities for the modeling of flow boiling, the present investigation compares two different phase-tracking methods for the analysis of such phenomena: the volume of fluid (VOF) and the coupled level set—volume of fluid (CLSVOF) techniques. These interface tracking and reconstruction techniques are coupled with a phase change model that accounts for the mass and energy transfer source terms to the governing equations. The geometric domain is constituted by a silicon microgap 175 μm high with a substrate thickness of 50 μm, and populated with circular pin fins of 150 μm diameter, where the heat conduction is simultaneously solved with temperature dependent properties. The flow boiling regimes and their spatial and temporal evolution are compared between both methods by maintaining the operating conditions. Results indicate that both methods provide a good capability to predict major two-phase flow regimes observed in experimental studies with these types of arrangements. However, the CLSVOF offers a sharper interface reconstruction than the standard VOF method by predicting bubble nucleation and departure mechanisms more closely to experimental observations.

A Coupled Level Set and Volume of Fluid method for automotive exterior water management applications

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.