Buoyant Flow Research Articles

A study of the characteristics of smoke stratification in lateral point smoke exhaust tunnel

In order to study flow stratification behavior in lateral smoke exhaust mode, experiments were carried out in reduced-scale model and numerical simulations model. The characteristics of smoke layer interface, smoke layer thickness, vertical temperature and normalized shear velocity in tunnel with different heat release rates were analyzed. The flow pattern was visualized by a semiconductor laser. The stratification pattern was found to fall into three regimes. Buoyancy, inertia force and suction force, as three factors affecting the flow stratification of smoke, are related by a new dimensionless number. At region I (Frs<2.4), the buoyancy stratification was stable, and there is an obvious interface between the upper smoke layer and the lower cold air layer. At region II (2.4<Frs<4.8), the buoyant flow stratification was stable, but the stratification interface between smoke and cold air was unstable. At region III (Frs>4.8), the stratification becomes unstable, the mixing between smoke and cold air was intense, and there is no obvious stratification interface.

Numerical studies of hydrogen buoyant flow in storage aquifers

Understanding buoyancy-driven flow is essential for ensuring the safety, reliability, and efficiency of underground hydrogen storage in saline aquifers. In this study, we develop a three-dimensional (3D) numerical model of an aquifer for hydrogen storage, with an isothermal system at 323.15 K, to investigate the behavior of hydrogen buoyant flow. We perform a series of sensitivity simulations to examine the influence of storage formation heterogeneity, including Dykstra-Parsons coefficient, autocorrelation length, and permeability anisotropy, as well as fluid-rock interaction parameters, such as capillary pressure and relative permeability, on storage efficiency. We evaluate the efficiency of geologic storage containment by quantifying a defined metric “escape ratio,” which is the mass fraction of hydrogen in a presumed escape region over the total mass of hydrogen. Our results indicate that hydrogen escape ratios and migration characteristics are primarily influenced by formation heterogeneities. The escape ratio decreases as Dykstra-Parsons coefficient increases and permeability anisotropy ratio decreases. The specific hydrogen escape path is controlled by spatial structures (i.e., autocorrelation length). Inclusion of capillary heterogeneity results in a decrease in the escape ratio, and the escape region exhibits a smoother appearance in the absence of capillary heterogeneity trapping as compared to when it is modeled. As for fluid-rock interactions, the hydrogen escape ratio is highly susceptible to the exponent of Brooks-Corey relative permeability function. Nevertheless, the magnitude of the escape ratio variation is predominantly determined by formation heterogeneity.

Tightly coupled hyperbolic treatment of buoyant two-phase flow and transport in porous media

Buoyant incompressible multiphase flow and transport in porous media typically is simulated by coupling an elliptic flow equation with a hyperbolic transport description. The tight coupling between flow and transport either requires a fully implicit solution algorithm or very small time steps, if solved sequentially. In any case, however, a large linear system has to be solved each time step.Here a new solution approach is devised, which relies on solving a coupled hyperbolic system of conservation laws with an explicit finite volume method. Consequently, only local operations have to be performed, which is a great advantage in case of massive parallel simulations and if GPUs are employed.The devised method is based on the isothermal Euler equations with momentum source terms accounting for resistance due to the porous medium and buoyancy. In this system the pressure is proportional to the density and in case of very small Mach numbers and relative density variation, the computed velocity field is divergence free and converges towards the mean total volumetric flow in the porous domain. To account for saturation transport, the system was augmented by an additional hyperbolic equation. In order to obtain the numerical fluxes, a characteristic based approximative Riemann solver was developed and 2nd order accuracy in space and time is achieved by piecewise linear reconstruction.Two-phase flow test cases with buoyant plumes and a lock exchange problem demonstrate that the devised hyperbolic approach recovers the correct incompressible solutions. Numerical experiments also demonstrate that the method is accurate and efficient.Thus the devised method is very promising, and conceptually it also can be applied for flow and transport in heterogeneous media; but it remains to be investigated how well it performs for such cases.

Assessment of Engineering Turbulence Models in Buoyant Diabatic Turbulent Flow

Turbulent heat transfer in buoyancy-dominated flows is a challenging problem for computational fluid dynamics (CFD). Many authors attribute model error in these conditions to the Reynolds analogy. We leverage a brand-new direct numerical simulation database to evaluate the performance of several popular turbulence models in buoyant diabatic channel flow. We find that heat transfer results are relatively accurate, with a Nusselt number error less than 20%. However, the turbulent flow solution is very inaccurate, with wall shear overpredicted by up to 100%. This indicates significant turbulence model error in such flows. We determined that the dominant sources of model error are missing physics in the algebraic Reynolds stress framework and the simple buoyancy production term used in industrial CFD. We suggest that future modeling efforts focus on these two sources of model error. We demonstrate that the Reynolds analogy is not the dominant source of model error.

Experimental investigation on non-buoyant and buoyant flow mixing in a horizontally aligned T-junction at isothermal conditions

Periodically occurring temperature fluctuations in nuclear power piping systems have been linked to cracking and coolant leakage accidents. T-junctions where hot and cold fluids mix are particularly vulnerable. To study thermal mixing flow phenomena, an isothermal operating test bench was built using a sugar respectively a salt solution to model the cold fluid in the T-junction configuration. The experiments aimed to predict the flow phenomena of mixed fluids with different fluid densities. Different types of investigations of non-buoyant and buoyant flow mixing were conducted using qualitative and quantitative measurement techniques, such as flow visualization, planar laser-induced fluorescence method, and wire mesh sensor measurements. Jet-formation and mixing behavior (up- and downstream) were characterized by the momentum ratio and a Richardson number. Additionally, non-buoyant flow conditions as well as buoyant flow with unstable/stable stratification have been summarized and clustered in non-dimensional flow maps. Results showed that wall- and deflecting-jet formations are a risk pattern for thermal fatigue. These were identified based on mean and fluctuating mixing scalar distribution as well as spectral analysis of the mixing scalar fluctuations. The peak frequencies in the non-buoyant case were linked to the axial motion of the Kármán-like vortices, while in the buoyant mixing case, the shear layer vortices resulting from Kelvin-Helmholtz instabilities were responsible.

Dispersion of a gyrotactic micro-organism suspension in a vertical pipe: the buoyancy–flow coupling effect

Understanding the transport of micro-organisms in pipes is crucial to many fundamental problems, such as bioconvection and biodiesel production. In this work, we investigate the velocity profile and dispersion of a suspension of negatively buoyant, gyrotactic micro-organisms in a vertical pipe. With an imposed flow rate, the non-uniform radial cell concentration typical of gyrotaxis distorts the simple Poiseuille flow through inhomogeneous buoyancy, which in turn affects the cell concentration distribution. By solving the fundamental Smoluchowski equation and the Navier–Stokes equation simultaneously, we account for this bidirectional buoyancy–flow coupling effect. Asymptotic dispersion coefficients, namely, drift velocity and dispersivity, are further calculated with the obtained radial velocity and cell concentration profiles, which are assumed to be steady, symmetric and axially invariant. Using the gyrotactic micro-organism Chlamydomonas augustae as an example, detailed results are given to illustrate the effect of buoyancy–flow coupling. In downwelling flows, the buoyancy–flow coupling effect intensifies with the Richardson number $Ri$ quantifying the mean cell concentration, but is strongest at a moderate flow strength. The buoyancy–flow coupling effect significantly enhances the velocity and cell concentration in the central region, as well as the drift velocity and dispersivity. In contrast, the buoyancy–flow coupling effect is comparatively limited in upwelling flows, due to the dominant influence of the no-slip boundary condition imposed at the wall. Comparisons with predictions of existing approximate models are also presented.

Numerical investigation of flow and heat transfer of supercritical carbon dioxide in the vertical helically-coiled tube under half-side heating condition

ABSTRACT The supercritical boiler is one of the ways to enable sustainable energy development. Its revolution cannot be separated from the study of the characteristics of supercritical carbon dioxide in a spiral pipe. This research article provided an industrially compliant model of a water-cooled wall spiral pipe with one-side heating for heat transfer. The simulation was set for various parameters including P = 30.42 MPa, Tin = 578–643 K, q = 105–180 kW/m2, G = 1784–2348 kg/m2s. The article discussed in detail factors such as buoyancy and secondary flow for these cases. The results showed that in the range of high parameters, mass fluxes, heat fluxes, and inlet temperature all had a substantial influence on the temperature and velocity fields, with the mass flux showing a non-monotonic trend on the HTC and the heat flux having a more subtle influence on the HTC. The inhomogeneous heating pattern affected the buoyancy and secondary flow motion, changing the temperature field in the tube, and enhancing the velocity field at the bend and on the heating side. A new empirical correlation for supercritical CO2 with non-uniform heating was proposed.

Buoyant Flow of H2 Vs. CO2 in Storage Aquifers: Implications to Geological Screening

Summary Hydrogen will play an important role in the quest to decarbonize the world’s economy by substituting fossil fuels. In addition to the development of hydrogen generation technologies, the energy industry will need to increase hydrogen storage capacity to facilitate the development of a robust hydrogen economy. The required hydrogen storage capacity will be much larger than current hydrogen and natural gas storage capacities. There are several geological storage options for hydrogen that include depleted hydrocarbon fields and aquifers, where more research is needed until the feasibility of storing hydrogen at scale is proved. Here, we investigate the buoyant flow of H2 (as a working gas) vs. CO2 (as a cushion gas) separately in a representative storage aquifer. Buoyant flow can affect the maximum storage, capillary trapping, likelihood of leakage, and deliverability of aquifer-stored hydrogen. After building a 2D geological reservoir model initially filled with saline water, we ran numerical simulations to determine how hydrogen placed at the bottom of an aquifer might rise through the water column. The Leverett j-function is used to generate heterogeneous capillary entry pressure fields that correlate with porosity and permeability fields. Hydrogen viscosities were based on the Jossi et al. correlation, and the density was modeled using the Peng-Robinson equation of state. We then simulated several scenarios to assess flow during short- (annually) and long- (several years) term storage. For comparison purposes, we also ran CO2 storage simulations using the same geological model but with CO2-brine-rock properties collected from the literature. For a representative storage aquifer (323 K, 15.7 MPa, and mean permeability of 200 md), significant fingering occurred as the hydrogen rose through the saline water column. The hydrogen experienced more buoyant flow and created flow paths with increased fingering when compared with CO2. Individual hydrogen fingers are thinner than the CO2 fingers in the simulations, and the tips of hydrogen finger fronts propagated upward roughly twice as fast as the CO2 front for a typical set of heterogeneity indicators (Dykstra-Parson’s coefficient Vdp = 0.80, and dimensionless autocorrelation length λDx = 2). The implications of buoyant flow for hydrogen in saline aquifers include an increased threat of leakage, more residual trapping of hydrogen, and, therefore, the need to focus more on the heterogeneity and lateral correlation behavior of the repository. If hydrogen penetrates the caprock of an aquifer, it will leak faster than CO2 and generate more vertical flow pathways. We identify possible depositional environments for clastic aquifers that would offer suitable characteristics for storage.

Thermals from finite sources in stable and unstable environments

The rise of thermals in the atmosphere has attracted a lot of attention since the early work of Morton et al. (Proc. R. Soc. Lond. A, vol. 234, 1956, pp. 1–23), who proposed that entrainment into a thermal was proportional to the surface area of the thermal and to the mean vertical velocity of the thermal. This paper presents new analytical solutions for the heights of rise of buoyant thermals in both stably and unstably stratified environments, for both negatively and positively buoyant sources, and where the sources have different size and strength (momentum) characteristics. The limiting cases of these analytical solutions are consistent with previous work. These analytical solutions do not appear elsewhere, and provide a compact set of equations that are easy to apply to a wide range of circumstances. The solutions are dependent upon the entrainment hypothesis, which is of course only an approximation, but the simplicity of the analytical solutions allows easy calculation and additional insights. These include the fact that while heights of rise are strongly dependent on both source strength and size for flows in stable environments, the dilution at the top of rise is independent of the source momentum. Further, in a stable environment, there is a conserved quantity that has dimensions proportional to vertical momentum. For negatively buoyant flows in an unstably stratified environment, thermals having low initial momentum will reach a maximum height, while thermals with high initial momentum will entrain sufficient buoyant environmental fluid that they will eventually become positively buoyant and continue to rise indefinitely.

Turbulent plumes above a heated plate

Our focus concerns the turbulent convective flow above a uniformly heated high-aspect-ratio rectangular plate on $z=0$ . Prior to this study, classic plume theory could not be applied directly as the Richardson number is ill-defined at the plate. Guided by observation, conservation equations are posed for the near-plate region where the attached buoyant flow is predominantly horizontal. Analytical solutions under the Boussinesq approximation reveal this to be a dynamically invariant region where the attached ‘plumes’ grow linearly toward the plate centreline, their merger forming an ‘apparent’ source for the vertical plume above. Coupling predictions with data from flow visualisation and temperature measurement, we deduce the half-width $0.72b_0$ , height ${z=0.46b_0}$ and finite Richardson number $({\sim }18)$ of an apparent source from which plume theory can be applied to model the plume above a heated plate of width $2b_0$ . Finally, practical implications of this advancement to the analytical theory of turbulent plumes are noted.

Inspection of unsteady buoyancy and stagnation point flow incorporated by Ag-TiO2 hybrid nanoparticles towards a spinning disk with Hall effects

The viscous flow across a rotating body is an emblematic phenomenon in many production processes, particularly in systems involving rotating disks. This study discusses the impact of buoyancy force and Hall effects on the time dependent stagnation point flow of Ag-TiO2/water hybrid nanofluid (HNF) flow over a rotating disk together. The Ag-TiO2/water HNF flow is investigated for two cases: assisting and opposing flow. Utilizing the appropriate similarity transformations, the partial differential equations (PDEs) representing the heat transfer problem are altered to ordinary differential equations (ODEs). The governing equations are solved numerically employing the “bvp4c function in MATLAB”. The current results are validated by comparison with the available literature and a very close precision is obtained. The influence of the primary relevant parameters on the properties of flow, and heat transmission rate is depicted graphically. The azimuthal and radial velocities of HNF flow are greater for assisting flow. The thermal profile of Ag-TiO2/water HNF flow is greater for opposing flow. The greater values of the Reynolds number surge the HT rate on the surface. The outcomes of this study will be useful in many fields that utilize applications of rotating disk systems such as rotor-stator systems, power generators, geothermal extraction, computer storage devices, engines in gas turbines, brakes, gears, and flywheels.

Viscous heating and instability of the adiabatic buoyant flows in a horizontal channel

The stability of buoyant flows occurring in the mixed convection regime for a viscous fluid in a horizontal plane-parallel channel with adiabatic walls is investigated. The basic flow features a parallel velocity field under stationary state conditions. There exists a duality of flows, for every prescribed value of the mass flow rate across the channel cross-section, caused by the combined actions of viscous dissipation and the buoyancy force. As pointed out in a previous study, only the primary branch of the dual solutions is compatible with the Oberbeck–Boussinesq approximation. Thus, the stability analysis will be focused on the stability of such flows. The onset of the thermal instability with small-amplitude perturbations of the basic flow is investigated by assuming a very large Prandtl number, which is equivalent to a creeping flow regime. The neutral stability curves and the critical parametric conditions for the onset of instability are determined numerically.

Analysis of the High-Pressure High-Temperature (HPHT) growth of single crystal diamond

A multi-scale, computational model is developed to describe the growth characteristics of single-crystal diamond in the High-Pressure, High-Temperature (HPHT) process. This model is the first to connect phase-change kinetics governing crystal growth to the continuum transport of carbon through the growth cell. Results show the importance of convective transport driven by buoyant flow in the metallic solvent, which increases the growth rate by nearly an order of magnitude over that obtained under diffusion alone. Parametric studies show how crystal growth may be kinetically-limited or transport-limited, depending on the value of the macroscopic kinetic coefficient. Estimating this kinetic coefficient from growth experiments yields a phase-change Damköhler number of unity, indicating a mixed regime where phase-change kinetics and transport are comparable and strongly coupled in this system. Mechanisms responsible for slowing growth as the crystal size increases are explained. Supersaturation inhomogeneities along the facets of larger crystals are predicted, which may be relevant to solvent inclusion formation during growth.

Laboratory study on movement characteristics of a river plume using particle image velocimetry

Rivers are important passages for land-based materials transported to the sea, such as fresh water, sediment, pollutants, and nutrients. River discharge with land-based materials will form a river plume with a buoyancy flow. The river plume is subject to the interaction between nearshore runoff with seawater. In this study, the movement characteristics of the river plume are investigated based on particle image velocimetry (PIV) and the dye tracing method. It is found that the change of flow rate and environmental water density will shape the river plume pattern in both the plan view and the side view. The combined effect of flow rate and environmental water density could be described by the Froude number. The river plume has a free surface in the x-z plane and the horizontal velocity of the plume can be fitted with a 1/2 Gaussian distribution curve. The change of flow rate has little effect on the type of plume thickness curve, while the increase of environmental water density will change the thickness curve type of the river plume. The stable thickness of the river plume increases with the increase of the Froude number. The maximum value of turbulent kinetic energy is located in the middle layer, and the increase of the flow rate or the density difference leads to the increase in the turbulent kinetic energy.

Upward flame spread over discrete thin solids separated by heat-absorbing inert materials

Flame spread over discrete solid fuels has been of key research interest in the past few decades. Most studies considered an array of discrete fuels separated by air gaps or heat-insulating inert materials. The effects of heat loss due to the discrete configuration are not well understood. The present study aims to bridge this knowledge gap. A series of experiments are performed using a vertical array of thin discrete fuels separated by heat-absorbing inert materials of different thicknesses. For comparisons, experiments are also performed using discrete fuels separated by air gaps and using continuous fuel. The flame base spread rate is found to be generally higher in discrete fuel than in continuous fuel configurations, due to a reduced fuel load per unit length. It is also found that the air and inert gaps have opposite effects on the solid burning rates. The air gaps break the no-slip boundary, allowing the laterally entrained buoyancy flow (normal to the sample surface) to push the flame closer to the samples. This leads to an enhanced heat flux on the sample surface and an increased solid burning rate. On the other hand, the inert materials retain the flow boundary profile and act as a heat sink during flame spread, thereby reducing the solid burning rate. As the inert thickness increases, flame spread rate and solid burning rate decrease. Based on these observations, an existing model for flame spread rate is updated by incorporating the heat-absorbing effects of the gaps. The correlation is validated using the experimental data.

Non-Similar Solutions of Dissipative Buoyancy Flow and Heat Transfer Induced by Water-Based Graphene Oxide Nanofluid through a Yawed Cylinder

The fluid flow through blunt bodies that are yawed and un-yawed frequently happens in many engineering applications. The practical significance of deep-water applications such as propagation control, splitting the boundary layer over submerged blocks, and preventing recirculation bubbles is explained by the fluid flow across a yawed cylinder. The current work examined the mixed convective flow and convective heat transfer by incorporating water-based graphene oxide nanofluid around a yawed cylinder with viscous dissipation and irregular heat source/sink. To investigate the heat diffusion across the system of buoyancy effects, the mathematical formulation of the problem was modeled in terms of coupled, nonlinear partial differential equations. The boundary value problem of the fourth-order (bvp4c) solver was operated to find the non-similarity solution. The outcomes indicated that the velocity in both directions enlarged owing to the higher impacts of yaw angle for the phenomenon of assisting flow but decreased for the instance of opposing flow, while the temperature of nanofluid increased because of heightened estimations of yaw angle for both assisting and opposing flows. In addition, with larger impacts of nanoparticle volume fraction, the shear stresses were enhanced by about 0.76% and 0.93% for the case of assisting flow, while for the case of opposing flow, they improved by almost 0.65% and 1.38%, respectively.

Buoyancy flow of nanohybrid fluid over a rotating sphere imperiled to convective and viscous heating

The thermal radiation and convective condition principles were working on specific functions like gas turbines, electrical fuel, renewable energy, projectiles, nuclear power plants, aerospace engineering, and thermal transportation. Considering the aforementioned functions, the present analysis inspected the stagnation point hybrid nanofluids movement over the rotating sphere on the behavior of viscous dissipation and thermal radiation. Silver and Ferrous nanoparticles including the host fluid water were held into affected the flow. The presence of convective boundary conditions is incorporated within the system. Applying appropriate correspondence factors, nonlinear governing equations were transformed with ordinary differential equations. This finite element method is applied to find the mathematical solutions to the boundary conditions and simplified equations. These outcomes convey to temperature was decreased about accelerated factor, although primary velocity was found into increased. The heat transfer was magnified by thermal Biot number, and that rate of development was greater about hybrid nanosuspension. The heat transport method was reduced by the Eckert number; also that reduction rate was similarly dull on hybrid.

Non-Darcy nanoliquid buoyant flow and entropy generation analysis in an inclined porous annulus: Effect of source-sink arrangement

In several engineering and industrial applications, the primary challenge in the design of thermal devices is to minimize the entropy production with maximum energy dissipation so that the system efficiency could be enhanced. In particular, an inclined partially heated annulus is far challenging due to the presence of both tangential and normal gravity components, which produces major impacts on the fluid movement and associated transport rates as well as entropy production. From several important applications point of view, the current investigation is mainly focused to address the combined impacts of source-sink arrangements as well as the annular inclination on buoyant nanoliquid motion, thermal dissipation along with irreversibility distribution in a tilted porous annulus. The governing model equations are numerically solved by utilizing the finite difference based time-splitting and relaxation techniques. Using second-order finite difference approximation, the partial derivatives are approximated and the resulting system of algebraic equations are inverted using Thomas algorithm. The influence of various controlling parameters such as geometric inclination angle, nanoparticle shape, Darcy number, length and position of source-sink on fluid movement, thermal and entropy distribution are scrutinized in detail. Through a wide range of numerical experiments, it has been found that the annular inclination angle and location of source-sink arrangement plays a vital role on fluidity and flow patterns of nanoliquid in the porous saturated annulus. For smaller size of source-sink pair, higher thermal dissipation with minimal entropy production could be achieved, which is an important observation for the design of thermally efficient systems. We have also noticed that a better thermal transport rate with minimum irreversibility rate could be attained for a particular source-sink arrangement, in particular for γ=0∘, the staggered positioning of source-sink pair is beneficial rather than in-line arrangement. Among the various parameters arising in this analysis, the nanoparticle shape has been one of the key parameters to test the thermal efficiency. It has been predicted that the blade shaped nanoparticle induces better thermal efficiency, among the five different shapes of nanoparticle. The outcomes of this analysis could be utilized in applications, such as solar systems, electronic equipment cooling and heat exchangers.

Scaling analysis of buoyant boundary layer flow induced by flux heating with a spatial gradient at Pr ≪ 1, Pr ∼ 1 and Pr ≫ 1

Buoyancy induced convective boundary layer flow is investigated with a scale law analysis in this study. Thermal forcing at the heated wall adopts the second-type boundary condition, and a spatial gradient is specified for the heat flux profile. A full range of Prandtl number is considered and separately analyzed, i.e. Pr << 1, Pr ∼ 1 and Pr >> 1, since the convective flow fundamentally differentiates for the three Pr ranges. Important scale laws quantifying different states of the transient flow are determined by the scaling analysis and they are validated against numerical calculations. The comparison suggests that the proposed scale laws could satisfactorily quantify the boundary layer flow and the corresponding regression constants R2 are around 0.999. The results indicate that scale laws for the three Pr ranges differ only in the Pr term and the Rayleigh number, streamwise location and heating parameter dependencies are identical. It is also demonstrated that, in the start-up state, the boundary layer growth is always two-dimensional at non-zero spatial gradient conditions and the heated wall temperature increases temporally according to τ1/2, which are profoundly different from the extensively investigated isothermal problems. The present work also identifies a special flow condition. That is, when the heat flux gradient equals 2, the heated wall temperature and characteristic velocity of the flow are reduced to vary linearly with streamwise location and the thermal boundary layer thickness becomes independent of streamwise location.

Performance analysis of step type solar still and comparison of the performance with evacuated tube collector coupled with single slope step type solar still

This research project aims to address the growing need for freshwater in regions affected by water scarcity, particularly in coastal and desert areas. The focus is on evaluating the effectiveness of a solar-powered desalination system, which utilizes a single slope step type solar still and an Evacuated Tube Collector (ETC) to produce fresh drinkable water. Additionally, Computational Fluid Dynamics (CFD) analysis is conducted to gain insights into the natural convection of heat transfer within a glass tube, which creates a buoyant flow of saline water. The design consists of a solar evacuated tube, which heats up due to the exposure to sun rays and this heat is transferred to the impure/saline water (effluent). The water is then discharged to a single slope step type solar still which absorbs energy from sunlight and increases the evaporation rate in the solar still. Thus, the water evaporates and is then condensed by the inner surface of the glass roof hence purified water is collected. The CFD flow analysis of incompressible fluid under the effect of gravity in the transient condition is carried out for ETC in the ANSYS workbench. Also, fluid flow analysis of single slope step type solar still consisting of ten steps with a water depth of 3 cm in multiphase conditions using the VOF model is carried out to obtain the amount of distillate output per day in fair weather conditions in the location 13.2848⁰ N, 74.7486⁰ E in Katapady, Udupi. The amount of distillate collected as a result of CFD analysis was found to be 5.195 kg/day. The contours obtained from the steady state analysis for solar still showed the distribution of temperature, solar heat flux, and mass flow rate. The transient analysis of the ETC assisted well in obtaining the temperature in the ETC collector tank and the variation in solar radiation throughout the day. The contours of ETC showed the buoyant flow of water under natural convection, velocity distribution, density distribution and solar irradiation distribution on glass walls.