DescriptionThis project simulates two-phase flow of water and air inside an open channel with a 180-degree bend using ANSYS Fluent. This is fundamentally a free-surface flow problem: the water moves with an open, deformable interface between the liquid and the air above it, and accurately capturing the position and shape of that free surface is the central modeling challenge. To handle it, the multiphase VOF (Volume of Fluid) model is used — the standard approach for free-surface currents — with air defined as the primary phase and water as the secondary phase. Because the water flows with a free surface inside the channel, the open channel flow sub-model is also employed, with the water level set at 0.2 m.A stream of water 0.2 m deep, with a mass flow rate of 94.83 kg/s, enters the channel and, after traveling through the 180-degree arc, exits the outlet at atmospheric pressure. For the upper boundary of the channel — where air passes — a relative pressure condition of 0 Pa is applied.Geometry & MeshThe model was built in 3D using Design Modeler. It is a channel with a rectangular cross-section following a 180-degree arc; the cross-section is 1 m wide and 0.7 m high. Meshing was performed in ANSYS Meshing using a structured grid of 2,316,480 elements, shown in the figure below.MethodologySeveral assumptions underpin the simulation: a pressure-based solver is used, the simulation is steady, and gravity acts at −9.81 m/s² along the vertical axis.Viscous model — RNG k-epsilon with standard wall functionsMultiphase model — VOF with 2 Eulerian phases (air and water), implicit formulation, the open channel flow sub-model, and sharp interface modelingBoundary conditions — Inlet: mass flow inlet with a free-surface water level of 0.2 m, bottom level of 0 m, water mass flow rate of 94.83 kg/s, and air mass flow rate of 0 kg/s; Outlet and top: pressure outlet at 0 Pa gauge; inner, outer, and bottom walls: stationaryMethods — SIMPLE pressure-velocity coupling; second-order for pressure; second-order upwind for momentum; compressive scheme for volume fraction; first-order upwind for turbulent kinetic energy and turbulent dissipation rateInitialization — standard method, with 0 Pa gauge pressure, zero velocity in all directions, water volume fraction 0, and air volume fraction 1ConclusionOn completion of the solution, three-dimensional contours of pressure, velocity, turbulent kinetic energy, and the volume fractions of water and air within the 180-degree bend were obtained. Because the VOF model tracks the free surface directly, the results reveal how the water surface deforms as the flow negotiates the curve — including the superelevation of the water on the outer wall of the bend, where the centripetal effect raises the free surface, and the corresponding drop along the inner wall. This redistribution of water depth and velocity around the arc is precisely the behavior that free-surface modeling is designed to capture, making the VOF and open-channel approach essential to obtaining physically meaningful results.

Wide-Edge (Broad-Crested) Spillway — ANSYS Fluent CFD Simulation TrainingIntroductionA wide-edge (broad-crested) spillway is a cascading structure with a long horizontal crown aligned with the flow direction, such that the error arising from the hydrostatic pressure distribution can be neglected thanks to the acceleration of the radial flow. These spillways operate so that the upstream flow is subcritical while the flow over the spillway itself becomes supercritical, creating a flow-control section above the crown. One characteristic of these structures is that, a short distance from the crown, the flow lines run nearly parallel.In this type of spillway, the crest is wide and substantial relative to the other dimensions. The crowns may be wide, horizontal, or follow a specific curvature. Although they can be used to measure discharge, they serve most often as dam spillways — and sometimes as the dam itself, when water is allowed to pass through — and can store large volumes of water when needed.Project DescriptionThis project investigates the flow inside a wide-edge spillway using ANSYS Fluent. There is a deliberate elevation difference between the main channel and the sub-channel, in part to store a portion of the flowing water. The RNG k-epsilon model solves the turbulent flow equations, while the multiphase VOF model captures the two phases of water and air within the open channel. Water enters the channel at a mass flow rate of 65 kg/s and passes into the second channel after striking the middle section of the spillway.Geometry & MeshThe geometry was created in ANSYS Design Modeler and meshed in ANSYS Meshing using a structured grid, for a total of 981,900 elements.MethodologySeveral key assumptions underpin the model. The simulation uses a pressure-based solver and is run as steady-state, so the results do not vary with time. Gravity is applied at −9.81 m/s² in the Y direction.Turbulence is modeled with the RNG k-epsilon model using standard wall functions, and the two phases — air as the primary phase and water as the secondary phase — are handled with the VOF approach. Water enters through a mass-flow inlet (65 kg/s) defined as an open-channel boundary, with a free-surface level of 0.08 m, a bottom level of 0 m, and density interpolation taken from the neighboring cell. The outlets are set as pressure outlets, and the walls are treated as stationary.For the solution methods, pressure–velocity coupling uses the SIMPLE scheme. Pressure is discretized with PRESTO! and momentum with second-order upwind, while volume fraction, turbulent kinetic energy, and turbulent dissipation rate all use first-order upwind. The solution is initialized with the standard method: gauge pressure 0 Pa, velocity 0 m/s, turbulent kinetic energy 1 m²/s², turbulent dissipation rate 1 m²/s³, and water volume fraction 0.ResultsThe water volume fraction contour shows that, because of the height difference and the absence of any inlet flow in the sub-channel, the water volume fraction takes nonzero values in the upper part of the sub-channel. Once the solution is complete, 3D contours of pressure, velocity, volume fractions, and related quantities are extracted and presented.

Sand Particle Sedimentation CFD Analysis, ANSYS Fluent TrainingIntroductionThis analysis presents a computational fluid dynamics (CFD) study of sedimentation behavior for three different sand particle sizes using ANSYS Fluent. The study examines how sand particles of varying sizes behave during sedimentation within a fluid medium, offering insight into settling patterns and particle distribution — information valuable for environmental engineering, sediment transport, and water treatment applications.The geometry was designed in ANSYS Design Modeler as a cylindrical domain, visible through the circular cross-section in the mesh. The domain was optimized to accurately capture particle sedimentation behavior under gravitational influence.ANSYS Meshing was used to generate a structured hexahedral mesh containing 388,797 elements, providing sufficient resolution to capture flow dynamics, turbulence effects, and particle distribution throughout the domain.MethodologyA pressure-based, steady-state solver was used to capture the equilibrium state of particle distribution within the fluid. The RNG k-epsilon turbulence model with standard wall functions was selected to represent the turbulent fluid-particle interaction occurring during sedimentation.The Eulerian multiphase model with implicit formulation was applied to simulate the interaction between the fluid phase and three distinct sand particle sizes — small, medium, and large. Gravitational effects were enabled throughout the simulation to accurately capture the sedimentation process.ResultsDensity contours reveal the distribution of the fluid-particle mixture across the domain, ranging from 998.20 kg/m³ to 1114.53 kg/m³, with higher densities concentrated near the bottom — reflecting particle accumulation due to sedimentation.Static pressure contours range from -80.92 Pa to 200.36 Pa, following a primarily vertical gradient with higher pressures near the domain's base, consistent with hydrostatic pressure distribution and the presence of settled particles.Volume fraction contours for each particle size reveal distinct settling behavior:Large particles (sand-l) reach a maximum volume fraction of 0.32, showing clear stratification and rapid settling concentrated near the bottom of the domain.Medium particles (sand-m) show a maximum volume fraction of 0.30, following a similar distribution pattern to the large particles but with a slightly more diffuse upper boundary.Small particles (sand-s) also reach a maximum volume fraction of 0.32, but remain far more uniformly distributed throughout the domain, indicating slower settling and greater suspension within the fluid.The water phase's volume fraction ranges from 0.37 to 1.00, complementing the particle distribution results.Vertical volume-fraction profiles at the outlet boundary further quantify this size-dependent behavior:Large particles show a sharp rise near the bottom, peaking at roughly 0.30.Medium particles exhibit a more gradual increase, peaking at approximately 0.28 near the bottom.Small particles maintain a much more uniform concentration throughout most of the domain height, peaking at only around 0.035.These results clearly illustrate size-dependent sedimentation behavior — larger particles settle rapidly and form distinct layers, while smaller particles remain largely suspended throughout the fluid. The findings offer practical insight into particle settling dynamics relevant to sediment transport and particle separation processes across a range of engineering applications.

Pollution Spread in a Stagnant River, ANSYS Fluent TrainingDescriptionThis project simulates the entry and spread of a pollutant into a stagnant river using ANSYS Fluent.The core of this case is open-channel flow — flow in a channel or river whose upper surface is open to the atmosphere and free to deform, rather than being fully enclosed by walls. In open-channel problems the position and shape of the free surface is part of the solution, and gravity governs how the water and anything riding on it settle and move. A river receiving a discharge is a natural example: the pollutant enters at the surface and spreads across it, so tracking that free surface is essential, which is exactly what the open-channel (free-surface VOF) approach is built for.The application itself is an environmental one. Water pollution from industrial waste is a serious concern: chemical by-products discharged into rivers endanger aquatic life and can enter the human food chain through it, causing disease. Simulating how a pollutant disperses once it reaches a river helps predict how far and how fast contamination travels.The 3-D geometry was built in Design Modeler, with a river inlet width of 11.05 m. The domain was meshed in ANSYS Meshing with 161,562 elements, and because the spreading process evolves in time, a transient solver is used.Simulation MethodologyThe two phases — water and pollutant — are handled with the VOF multiphase model. The pollutant enters through a non-uniform profile partway along the river and diffuses into the water. Because its density is lower than that of water, it floats and spreads along the free surface. Turbulence is solved with the realizable k-ε model using scalable wall functions, pressure-velocity coupling is SIMPLE, and momentum and the volume fraction use second-order upwind discretization. The river water itself is initially stagnant, and the pollutant enters at 8 m/s.Results & ConclusionAfter solving, contours of velocity, pressure, and pollutant volume fraction were obtained. The results show the pollutant progressively diffusing into the river water over time, with the pressure near the pollutant inlet higher than elsewhere. The cross-sectional pressure contour also shows pressure increasing with depth, as expected for a body of water under gravity.

DescriptionThis project simulates pollution transport in a meandering river using ANSYS Fluent, investigated through CFD analysis. Water pollution is the contamination of water bodies — usually the result of human activity — in a way that harms their legitimate uses. Such pollution prevents a body of water from delivering the ecosystem services it would otherwise provide, and it is broadly classified as either surface water pollution or groundwater pollution.The model was built in 3D using Design Modeler. The river's width at the inlet is 14.035 m, and the pollutant enters through two circular profiles, each 3 m in diameter. Meshing was performed in ANSYS Meshing, producing 762,433 elements. Because of the time-dependent nature of the problem, a transient solver was used.MethodologyThis study employs the VOF (Volume of Fluid) multiphase model to solve the two-phase flow field. To represent the free surface of the river, the open channel option within the multiphase module was enabled, allowing the air–water interface and the gravity-driven surface flow to be captured accurately.Pollutant enters the river through two circular inlet profiles near its start and then diffuses into the water. Because the pollutant is less dense than water, it accumulates at the river's surface, and the flow carries it downstream, spreading the contamination along the channel.The Realizable k-epsilon viscous model with scalable wall functions was used to resolve the turbulent flow. Pressure-velocity coupling was handled with the SIMPLE scheme. A second-order upwind scheme was applied to the momentum equations, while a first-order upwind scheme was used for the turbulent kinetic energy and turbulent dissipation rate. Water enters the domain at 35 m/s, and the pollutant enters at 5 m/s.ConclusionOnce the solution was complete, contours of velocity, pressure, pollutant volume fraction, water volume fraction, eddy viscosity, and streamlines were extracted and presented across different time steps.As the results show, the pollutant enters the river through the two circular inlet profiles and gradually diffuses across the water surface over time. Driven by the river's flow, the pollution spreads along the free surface and ultimately leads to widespread contamination of the channel.

Offshore Pipeline Considering Hydrodynamic Force, ANSYS Fluent CFD Simulation TrainingDescriptionThis project simulates seawater flow around an offshore pipeline using ANSYS Fluent.Offshore pipelines are a core part of marine engineering, carrying oil, gas, and other resources across the seabed between platforms and shore. As seawater waves pass over these pipelines, they generate drag and lift forces on the pipe. To keep the line safe and stable, it must be positioned so that it experiences the lowest possible hydrodynamic loading, which makes this kind of analysis important for offshore pipeline design.The 2-D model was built in ICEM and consists of a rectangular seawater domain with a circular cross-section representing the pipe. Two key geometric parameters govern the study: the pipe diameter (D) and the gap between the bottom of the pipe and the seafloor (e), expressed through the e/D ratio. The pipe diameter is fixed at 0.4 m, and two cases are considered, e = 0.2 m and e = 0.1 m, giving e/D = 0.5 and e/D = 0.25. The seawater domain is 12 m long and 3.24 m high.The model was meshed in ICEM using a structured grid of 135,417 elements. To capture the flow accurately, the mesh is refined near the pipe: the circumference of the circular section is split into five segments, and the cells closest to the pipe are smaller and of higher quality.Simulation MethodologyThe main geometric variable in this study is the pipe-to-seafloor gap ratio (e/D). Because the seawater motion is wavy rather than steady, the inlet velocity is defined as a wave-flow equation through a UDF. Likewise, the pressure inside the seawater is measured relative to atmospheric pressure and varies with the wave motion, so the wave (ambient) pressure is also imposed through a UDF. In total, the inlet horizontal velocity, the relative wave pressure, the turbulent kinetic energy, and the turbulence dissipation rate are all defined as UDFs.The goal is to compare the hydrodynamic forces on the pipeline over one full wave period and identify the optimal configuration. The seawater wavelength (the distance between two wave peaks) is 163.20 m, with a corresponding period of 10.3 s, giving a wave angular frequency of 2π/Tw = 2π/10.3 ≈ 0.61 rad/s. The maximum velocity at a wave peak is 2.729 m/s, and k_m and ε_m denote the maximum turbulent kinetic energy and the maximum turbulence dissipation rate, respectively.In the wave-pressure equation, H is the wave height and d is the seawater depth. The term −z is the height of the water column at the point where the dynamic pressure is evaluated, and d − (−z) is the distance from that point down to the seabed.Results & ConclusionAfter solving, we obtained two-dimensional contours of velocity and pressure, along with two-dimensional velocity vectors, for both cases (e/D = 0.5 and e/D = 0.25). These results are taken at the final instant of the simulation (10.3 s), i.e., at the end of one complete wave period.We also obtained time-history graphs of the drag and lift hydrodynamic forces and of the drag and lift coefficients, again for both e/D cases. Comparing the two configurations shows how the pipe's distance from the seabed affects the hydrodynamic loading, which is what determines the optimal placement of the line.

DescriptionThis study investigates water flow over the blades of a Horizontal Axis Water Turbine (HAWT) using ANSYS Fluent, with the goal of examining the velocity and pressure distribution across the blade surfaces. Turbines of this kind are central to marine and hydrokinetic energy engineering, where they harness the kinetic energy of moving water to generate power.Two regions are defined around the blades: a cylindrical zone immediately surrounding them, and a larger domain enclosing that cylinder. In the outer domain, the water behaves as an ordinary free stream, while in the inner cylindrical region the rotational motion of the blades induces a swirling, rotational flow.Several assumptions underpin the simulation. The analysis is steady-state, since the turbine is of the horizontal-axis type and time therefore has no bearing on the drag and lift forces. A pressure-based solver is used, and gravitational force is neglected.MethodologyThe model was built in 3D, with the blade cross-section based on an S814 airfoil whose coordinates were taken from the Airfoil Tools website and exported as a text file. Because the airfoil section scales up or down along the blade span, Excel was used to define the coordinates at each spanwise station. Each section was then drawn in SOLIDWORKS at the appropriate angle and position and imported into Design Modeler to construct the blades and turbine shaft. Within Design Modeler, the rotational water region around the blades and the larger free-stream domain were both created.Meshing was performed in ANSYS Meshing using an unstructured grid. To improve accuracy, a boundary-layer mesh was applied to the blade surfaces, and the final cell count reached 4,270,222.The rotation of the blades is modeled using the Frame Motion (MRF) method. The turbine blades rotate at 191 rpm while the surrounding water is treated as stationary; under this approach, the blades are held fixed and the water region around them is assigned a rotating frame turning at the same 191 rpm about the Z-axis. Because the simulation is steady-state, the Mesh Motion option is disabled — it applies only when time-dependent effects must be captured, whereas here the objective is simply to impose the rotational speed on the blades.The solution setup is summarized below:Viscous model — SST k-omegaBoundary conditions — velocity inlet at 1 m/s; pressure outlet at 0 Pa gauge; all walls set as stationarySolution methods — SIMPLE pressure-velocity coupling; second-order upwind discretization for pressure, momentum, turbulent kinetic energy, and turbulent dissipation rateInitialization — standard method, with an initial velocity of −1 m/s in the Z-directionConclusionOn completion of the solution, the velocity and pressure distributions over the turbine blades can be examined in detail through the corresponding contours. These results reveal how the water loads the blade surfaces and how the rotational flow develops within the cylindrical zone, providing the basis for evaluating the hydrodynamic performance of the horizontal-axis water turbine.

Kaplan Turbine CFD Simulation, ANSYS Fluent TrainingDescriptionThis project simulates a Kaplan turbine using ANSYS Fluent. Turbomachines, also known as fluid machines, are widely used across industry, making it essential to understand their behavior in a fluid environment. Turbomachines generally fall into two categories: the first group — such as fans and compressors — takes energy and transfers it to the fluid, while the second group extracts energy from the fluid and transfers it to the system, as seen in wind and water turbines. Kaplan turbines belong to this second category.Kaplan turbines are a type of inward-flow reaction turbine, among the most widely used turbine designs in industry, operating through a combination of axial and radial flow concepts. Water enters through an inlet tube that rotates around guide vanes, flowing tangentially through these vanes before being redirected into a spiral pattern by the runner's propeller blades — ultimately driving the runner's rotation.This project investigates water flow passing through a Kaplan turbine rotating at 3300 rpm. The geometry was designed in Design Modeler and meshed in ANSYS Meshing using an unstructured grid totaling 919,824 cells.MethodologyTurbine rotation was modeled using the MRF (Moving Reference Frame) approach, applied through the Frame Motion option. Rather than rotating the turbine blades themselves, the surrounding fluid is treated as rotating at a velocity matching the turbine's own rotational speed, implemented through the MRF tool within Cell Zone Conditions.ConclusionResults include 2D and 3D contours of pressure, velocity, and surface pressure, along with velocity vector fields illustrating the fluid's rotational motion around the turbine blades.The surface pressure contour reveals localized regions on the turbine blades experiencing notably reduced pressure — these areas represent potential sites where cavitation could occur, and warrant closer examination in subsequent, more detailed analysis to assess cavitation risk and its potential impact on turbine performance and blade integrity.

Kaplan Hydro Turbine Evaluation, ANSYS Fluent CFD Simulation TutorialDescriptionThis project evaluates a Kaplan hydro turbine using ANSYS Fluent. The Kaplan turbine is a propeller-type water turbine featuring adjustable blades, classified as an inward-flow reaction turbine — meaning the working fluid undergoes a pressure change as it passes through the turbine, giving up its energy in the process. Power is recovered from both the hydrostatic head and the kinetic energy of the flowing water, with the Kaplan design combining characteristics of both radial and axial turbines.This project studies the turbine's hydrodynamic behavior, with the rotor set to an angular velocity of 16.5 rpm. Boundary conditions include a constant mass flow rate of 1000 kg/s at the inlet, zero gauge pressure at the outlet, and symmetry conditions applied to all side walls, given their distance from the region of primary interest. The study also evaluates turbine performance through the resulting drag force.The geometry — a small-scale Kaplan turbine — was designed in Design Modeler and meshed in ANSYS Meshing using an unstructured grid totaling 9,861,922 cells.MethodologyTurbine rotation was modeled using the MRF (Moving Reference Frame) approach via the Frame Motion option, treating the fluid surrounding the turbine blades as rotating rather than the blades themselves. Given the turbomachinery nature of this simulation, a dedicated cylindrical zone was separated from the broader computational domain, with the fluid within this zone assigned a rotational velocity matching the turbine's own, implemented through the MRF tool within Cell Zone Conditions.ConclusionResults include 2D and 3D contours of pressure, velocity, and surface pressure, along with velocity vectors and streamlines illustrating the fluid's rotational motion around the turbine blades.The lowest pressure occurs at the turbine's leading edge, consistent with the highest velocity values occurring at the blade tip. Velocity contours further show that rotational velocity — and the influence of the associated source terms — increases with distance from the turbine axis. The pressure distribution along the turbine walls forms two distinct regions: a high-pressure zone upstream, before the flow interacts with the turbine, and a corresponding low-pressure zone downstream, behind the turbine geometry.The flow vectors also capture the wake region's resolved behavior — a central challenge in aerodynamic simulation of this kind — revealing a suction mechanism active at the turbine's lower sections and a blowing mechanism at the upper sections. A core vortex adjacent to the turbine body is likewise captured, offering insight into how the flow field is reshaped in close proximity to the rotating walls.

DescriptionThis project uses ANSYS Fluent to simulate a Darrieus-type vertical axis water turbine (VAWT) submerged in flowing water, applying the Dynamic Mesh method to capture rotation driven by the surrounding flow — a relevant application in marine renewable energy and hydrokinetic power generation. Unlike wind-based VAWTs, this turbine extracts kinetic energy directly from water flow, with its rotational axis perpendicular to the flow direction. The three-bladed turbine rotates freely in response to the fluid forces acting on it, allowing its performance under water flow conditions to be evaluated.MethodologyThe 3D geometry is built in DesignModeler, consisting of a large computational domain containing a three-bladed Darrieus turbine (0.5 m blade height), with the turbine center positioned 3 m from the inlet, 10 m from the outlet, and 0.75 m from the top and bottom domain surfaces. The domain is meshed in ANSYS Meshing using a hybrid grid — unstructured around the turbine body and structured elsewhere — totaling 7,422,668 elements.Water enters the domain at 1 m/s along the horizontal axis, with a pressure outlet at atmospheric conditions and symmetry conditions applied to the top and lateral surfaces. The turbine's rotation is captured using the Dynamic Mesh model, with a cylindrical sub-region isolating the turbine blades as rigid bodies. Rotational motion is defined with one degree of freedom (1-DOF), using a blade mass of 1 kg and moment of inertia of 3.09 kg·m². The simulation is run transient, over 50 seconds with a 0.05 second time step, consistent with the dynamic mesh approach.ConclusionResults include 2D contours of velocity, pressure, and turbulent kinetic energy, along with pathlines and velocity vectors on a plane through the turbine center. Turbine torque and other performance characteristics are also analyzed, providing insight into the turbine's power extraction behavior — relevant to marine hydrokinetic energy system design and evaluation.