Ryan Mozafari - CFD Projects

I am particularly interested in Computational Fluid Dynamics (CFD) to solve and predict many engineering and scientific problems in the area of thermal-fluid and energy. Applying such numerical methods can significantly help to prevent the experimental costs.

So far, I have carried out CFD simulations for a variety of academic and industrial thermal and fluid problems as follows:

Turbomachinery
Wind Engineering and Aerodynamics
Thermal Systems
Hydraulic Engineering and Open Channel Flow
Various Fluid Flow Problems

Turbomachinery

CFD Analysis of Centrifugal Compressor

Radial impeller is widely used in diesel engine turbochargers. In this project, a 3D model of centrifugal compressor impeller has been created and numerically investigated using CFD method. The effects of back swept angle about compressor performance are examined by using a radial back swept impeller designed. The ideal-gas air flow has been numerically analysed through the compressor blades.

The CFD results show that an appropriate back swept angle can improve the pressure ratio and volume flow rate of the compressor. The relative Mach number distributions are visualized and the reason that causes total pressure loses are analyzed. Shock wave can cause a loss of total pressure.

Design and Numerical Analysis of Centrifugal Pump

A centrifugal pump has been designed to provide a static head of 60 m with a water flow rate of 2200 m³/hrs. In this project, a 3D model has been created and numerically investigated using CFD method.

Centrifugal Fan

A conventional centrifugal fan was designed and numerically investigated by CFD tool. This particular centrifugal fan seems reasonable to be split into three components: Spiral, Impeller, and Suction. The objective of this 3D simulation was to predict the fan’s aerodynamic performance and identify key areas for design optimization.

CFD prediction of cavitation in an industrial centrifugal pump considering sediment particles

Cavitation is a challenging phenomenon that CFD engineers try to tackle and it occurs in many hydraulic applications such as pumps, and marine propellers. Cavitation may lead to structural damage due to the bubbles imploding when subjected to higher pressure, and it can also cause instabilities and increased noise. In this project, an industrial centrifugal pump has been numerically analysed. Water is supposed to flow through the pump, while the effect of sediment particles have been considered through discrete phase model (DPM).

CFD results show that cavitation occurs mainly due to sudden increase in local velocities creating low pressure pockets, resulting in local evaporation of the liquid and formation of two phase (liquid-vapor) flow. Liquid-vapor distribution contours clearly show where the total pressure is lower than the water vapor pressure, highlighting the sports with possible chance of cavitation. By cavitation around the pump impellers, the head of the pump will decrease in function of the net positive suction head (NPSH).

CFD Analysis of a radial-flow Pump

A radial-flow pump has been designed with the suction diameter of 94.9 mm, and impeller diameter of 212 mm. A 3D model has been created and numerically investigated using CFD method to predict the pressure change and flow characteristics.

Wind Engineering and Aerodynamics

Vertical axis hybrid wind turbine

Wind energy is a sustainable source of energy that respond positively to both global warming and energy demand, associated with the increasing population density in recent years.

In this project, a hybrid wind turbine has been numerically investigated where a 4 m/s wind velocity is subjected. This hybrid design integrates Savonius and Darrieus type turbines on the same shaft. The hybrid design is aimed to enhance the performances of the vertical axis turbines from wind turbine types and to extend their usage areas. This performance enhancement could be evaluated by comparing their performance indexes such as efficiency, torque, and tip-speed ratio with those of the conventional wind turbines.

Airfoil Stall

This transient simulation shows streamlines over a NACA airfoil by increasing angle of attack subjected to Much number of 0.6. A rotating moving mesh has been applied to achieve this condition. It is shown that by reaching the critical angle of attack a flow separation happens that dramatically reduces the pressure coefficient. Stalling phenomena is a serious problem that may happen in aviation. In such situation he pilot will notice the flight controls have become less responsive and may also notice some buffeting, a result of the turbulent air separated from the wing hitting the tail of the aircraft.

Wind flow simulation around a building

CFD has been utilized as the tool to predict the wind flow characteristics around the Sepid Building. Reynolds Stress Model has been utilized as the turbulence model while an air flow with a speed of 10 m/s is applied. The numerical results identified the critical locations which are affected with high wind velocity in the pedestrian area.

Natural ventilation analysis in a traditional wind catcher building using CFD

Windcatchers are traditional natural ventilation systems attached to buildings in order to ventilate the indoor air. In this project, natural ventilation of a traditional building with windcatcher structure has been predicted using a 3D steady RANS simulation.

Thermal Systems

Cooling performance of an exhaust gas recirculation (EGR) cooler with nanofluids

In this project, CFD tool has been utilized to predict the thermal performance of an exhaust gas recirculation (EGR) cooler when different nanofluid are selected as the coolant. Water was selected as the base fluid while Al2O3, Cu, SiO2, and TiO2 were selected as nanoparticles in a wide range of Reynolds numbers and various particle concentrations. The comparison results indicate the dominancy of aluminium-oxide nanoparticles over other nanoparticles due to showing a lower range of temperature (better cooling) and also higher convection heat transfer coefficient.

Geometrical improvement of a vortex tube for gas temperature separation

Vortex tube is a mechanical device that separates a compressed gas into hot and cold streams. The vortex tube has no moving parts and generally consists of a circular tube with nozzles and a throttle valve. High pressure gas enters the vortex tube tangentially through the nozzles which increases the angular velocity and thus produces a swirl effect. The hot exit is located in the outer radius near the far end of the nozzle and the cold exit is in the centre of the tube near the inlet nozzles. The gas flow divides to hot and cold layers. The gas closer to the axis has a low temperature and comes out through the cold exit and the gas near the periphery of the tube has a high temperature which comes out through the hot exit. This temperature difference is resulted due to the swirl flow inside the tube. In this project, the inlet flow has been studied at 2-45 bars pressure range with temperature of 300 K. The optimized ratio of length to diameter of the tube has been found to be 9.65, while the optimized ratio of tube diameter to nozzle diameter has been found to be 10 according to this project.

Cooling Performance Analysis of a CPU Heatsink

Overheating of the electronic components may damage or weaken the performance of electronic systems. Therefore, effective cooling of electronics is of great importance for manufacturers. In this project, a fan-forced cooling performance of a CPU heatsink has been investigated using CFD tool. The effect of forced convection heat transfer mechanism has been studied on the temperature distribution of heatsink.

Thermohydrodynamic Analysis of a Journal Bearing

hydrodynamic journal bearings are commonly used in machineries rotating at high speed for carrying heavy rotor loads. High speed operation of journal bearings leads to heat generation which lowers the viscosity of the lubricant and in turn affects the performance characteristics. In this project, the performance characteristics of a plain journal bearing was investigated using 3D CFD simulation. The pressure distribution was studied along the journal surface circumferentially and axially.

Thermal performance of a cylindrical heat pipe

Heat Pipes could be used to transfer thermal energy from a heat source to a heat sink with very small difference in temperature. There are three main sections in a heat pipe: the evaporator, adiabatic section and the condenser. In this project, a cylindrical heat pipe with different inclination angles of 0 (horizontal), 30, 60, and 90 (vertical) and different heating powers has been numerically investigated. The numerical model accounts for the thin-film evaporation, and Marangoni convection effects during phase change at the liquid–vapor interface.

Heat transfer enhancement using twisted cross-baffle turbulators in a heat exchanger tube

Computational Fluid Dynamics has been utilized to investigate the effect of different designs of cross-baffles (twisted, and simple) with different pitch ratios on heat transfer rate, friction factor and thermal enhancement. Baffles in twisted form were found to offer higher thermal enhancement factor than straight baffles.

Hydraulic Engineering and Open Channel Flow

Timber Wood Beam Falling into a Pool

A two-dimensional CFD simulation was carried out using a 2-phase VOF (Volume of Fluid) method which accounts for the dynamics of incompressible water flow with a free surface. A wood beam has been released above the water surface with a realistic 6 degree of freedom consideration. The water surface and object movement has been accurately predicted in a transient simulation.

Water flow patterns prediction in a dam

A 3-D CFD model of hydrodynamics in Ghadrooni dam reservoir was developed. The volume of fluid (VOF) model of flow was established to account for the effect of wind on hydrodynamics of the water. A k-ω SST turbulence model was applied for in steady-state conditions. The CFD results proved a strong effect of air flow on hydrodynamics, especially on the development of the water circulation pattern.

Wave Generator

A CFD simulation was carried out using a 2-phase VOF (Volume of Fluid) method which accounts for the dynamics of incompressible water flow with a free surface.

A floating wooden object (with 6 degree of freedom) has been considered on the by applying dynamic mesh in the CFD model, while a swinging wall generates the waves through the pool.

Transient water flow over a v-notch weir in a container

A transient CFD simulation shows how water spills over a v-notch weir at the middle of an open container, and finally maintains equal level through the space.

Various Fluid Flow Problems

CFD analysis of a hydrocyclone used for fine filtration

A hydrocyclone is a high-quantity gravity separation device used for separating slurry particles based on particle weight. The contaminated water arrives the hydrocyclone tangentially and makes a spiral flow motion through the system. The subsequent centrifugal force carries the particles toward the wall of the structure, and the heavy particles fall down and eventually become separated from the flow. The applications of hydrocyclones in industry vary from use as dryers in petroleum industries to removal of catalyst from gases to filtration of impure water. The most crucial factor affecting the performance of a hydrocyclone is its geometry. In this project, a CFD simulation with the Eulerian-Lagrangian approach including a discrete phase model (DPM) is used to predict the particle paths in the hydrocyclone.

CFD simulation of a mixing tank for the pharmaceutical industry

A numerical model has been carried out to predict the flow behaviour of water in fully baffled stirred tank. The VOF two-phase model has been taken into account in this regard.

Numerical analysis of a high speed dispersion mixer

A CFD model has been carried out to predict the liquid dispersion in a vessel. The VOF two-phase model has been taken into account such that air has been considered as a secondary phase above the liquid inside the vessel. Multiple Reference Frame (MRF) has been considered for the inner rotating fluid zone.

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