This work presents a numerical analysis of the ability of the high lift airfoil profile Selig S1223 for working as hydrofoil under water conditions. The geometry of the hydrofoil blade is designed through a suitable airfoil profile and then studied carefully by means of Computational fluid dynamics ((CFD)) in order to check its hydrodynamic behavior, i.e., including lift and drag analysis, and determinations of streamlines velocities and pressures fields. Finally conclusions on the use of this profile in a possible application for hydrokinetic turbine blades are detailed.

A numerical model is implemented to describe fluid dynamic processes associated with mid-latitude small-scale (10 km) upper ocean fronts by using modified state of the art Computational fluid dynamics tools. A periodic system was simulated using three different turbulent closures: 1) URANSReynolds Stress Model (RSM, seven equation turbulence model), 2) LES-Standard Smagorinsky (SS, algebraic model), and 3) LES-Modified Smagorinsky, introducing a correction for non-isotropic grids (MS). The results show the front developing instabilities and generating sub-mesoscale structures after four days of simulation. A strongly unstable shear flow is found to be confined within the mixed layer with a high Rossby number(R0>1) and high vertical velocity zones. The positive (negative) vertical velocity magnitude is found to be approximately O (10-3) m/s (O (10-2) m/s), one (two) order (s) of magnitude larger than the vertical velocity outside the sub-mesoscale structures, where the magnitude is stable at O (10-4) m/s. The latter value is consistent with previous numerical and experimental studies that use coarser grid sizes and therefore do not explicitly calculate the small scale structures. The nonlinear flow introduced by the sub-mesoscale dynamics within the mixed layer and the non-isotropic grid used in the calculations generates a disparity between the predicted horizontal wave-number spectra computed using the RSM model with respect to the linear eddy viscosity model SS. The MS approach improves SS predictions. This improvement is more significant below the mixed layer in the absence of flow nonlinearities. The horizontal spectra predicted with the RSM model fits a slope of -3 for large scale structures and a slope between -2 and -5=3 for turbulent structures smaller than 300 m. This work contributes to the investigation of the physical and methodological aspects for the detailed modelling and understanding of small scale structures in ocean turbulence.

In this paper three algorithms of Cyclic-Reduction, Parallel-Cyclic-Reduction and Parallel-Thomas are introduced to solve the Tridiagonal system of equations using GPUs and the effect of coalesced-memory-access and uncoalesced-memory-access to global memory are studied. To assess the ability of these algorithms, as a case-study the simulation of the lid-driven cavity flow have been compared to the results of Runtimes and physical parameters of the classical Thomas algorithm, executed on CPU. The maximum speed-up of these algorithms against CPU runtime is about 4.4x, 5.2x and 38.5x, respectively. Also, approximately a 2x speed-up achieved in coalesced-memory access on GPU.

Heat exchangers that use the Maisotsenko Cycle have high efficiency despite using evaporative cooling. Therefore, in this study, based on Computational fluid dynamics, the simulation of the Maisotsenko Cycle has been investigated. In this paper, the effects of all operational parameters such as temperature, inlet air huidity, air velocity in wet and dry channels, as well as geometric parameters such as the length of the heat exchanger and the height of the channels on the efficiency of heat exchanger have been studied. The simulation results showed that the heat exchanger has a favorable efficiency in different climatic conditions, so that wet efficiency for this heat exchanger varies from 103 to 115, but the increase in humidity will reduce the efficiency and the effectiveness of the heat exchanger. Also, the results showed that an increase in the velocity inside the dry and wet channels, respectively, decreases and increases the efficiency. Finally, the optimum ratio of the mass flow rate of wet channel to dry one is determined to be 1. 3.

Thickeners are the key units in the hydrometallurgical processing operations and used to separate solids from liquids. In this research, the pattern of mixture of the pulp and clear water phases in a mixing duct known as E-DUC was calculated through (CFD), and the effect of flow rate changes and solids content of the input feed on dilution before the feed well was studied. fluid dynamics were studied by modeling continuity and Navier-Stokes equations in Fluent version 14. 5. The k-ε library function was used to apply turbulent flow conditions and the mixture model was used to study multiphase flows. The flow rate and solids content of the feed under the factory’ s operational conditions were 605. 45 m3/h and 25%, respectively. In this study, dilution of the feed flowing into the feed well was calculated to be 19. 51 using simulations under operational conditions, which was an acceptable estimate of the existing dilution. Afterwards, by changing the flow rate of the feed, the effect of this parameter on dilution of the pulp input to the feed well was determined. By increasing the flow rate to 700 m3/h dilution levels rose to 28. 5 respectively.

Introduction: Cyclones are widely used to separate solid particles from the fluid phase. Due to the ease of construction, low running costs, and hard-working conditions at high temperatures, people's interest in using cyclones is increasing day by day. Engineers are generally interested in two parameters to perform a complete evaluation of the design and operation of a cyclone. These parameters are the particle collecting efficiency and the pressure drop inside the cyclone. The precise prediction of the pressure drop in cyclone is very important which it is directly related to operating costs. Computational fluid dynamics ((CFD)) is a diversified tool for predicting flow behavior in a wide range of design and operational conditions. Numerical solution of Navier-Stokes equations is the basis of all (CFD) techniques, which is the result of fast computer upgrades and a better understanding of the numerical resolution of turbulence. Materials and Methods: Regarding preliminary experimental tests and understanding the fluid flow, the flow rate of 0. 08 kg s-1 was selected as the flow rate. Six levels of inlet velocities 10, 12, 14, 16, 18, and 20 m s-1 were selected for understanding the effect of inlet velocity on the cyclone performance. The measurements were carried out using a hot-air anemometer (TSI-8484model with a resolution of 0. 07 m s-1 and an operating range of 0. 125 to 50 m s-1), and a pressure differential meter instrument (CPE310s-KIMO model) with an accuracy of 0. 1 Pa. The region is discretized as a finite volume in a set, called the region grid or mesh after discretization. For incompressible fluids, pressure-based and density-based solvers are used, respectively. Regarding the velocity of the material entering the cyclone and low Mach number, a pressure-based solver could be used in this study. The shear stress transport model (SST) is a modified version of the k-ω 2-equation model. This model combines the two turbulence k-ω and k-ε models. The Lagrangian discrete phase model in Ansys Fluent follows to the Euler-Lagrangian model. Defining the best type of boundary condition is important for solving the problem and extracting solving fields. The boundary conditions used in this study include the inlet velocity in the entrance of cyclone and output pressure in both the upper and lower output sections. Results and Discussion: In the results section, the results are initially validated by experimental results. Then, the parameters relating to separation efficiency and pressure drop are discussed. Finally, the tangential and axial velocities are considered as important parameters in the cyclone performance. One of the important issues in the cyclones is the static pressure because it completely affects the phenomenon of separation in the cyclone. The velocities of 16 m s-1 and 18 m s-1 have a good potential for use as the base velocity of the inlet fluid to the cyclone. The velocity of 20 m s-1 is not suitable for separation due to high-pressure drop related to high static pressure. The separation efficiency in the cyclone was 92 to 99% at all levels, the highest separation efficiency of 99% occurred at the velocity of 16 m s-1 and the lowest separation efficiency of 9% happened at the velocity of 20 m s-1. An increasing trend in axial and radial velocities occurred and the highest tangential velocity occurring in the input section. Considering the working conditions, the inlet velocities of 10 m s-1 to 16 m s-1 are appropriate for the turbulence intensity viewpoint. Conclusions: (1): The speeds 16 m s-1 and 18 m s-1 showed a good potential for use as a base velocity of the fluid to the cyclone. (2): The highest separation efficiency for the velocity of 16 m s-1 (99%) and lower isolation efficiency was obtained at velocity of 20 m s-1 (92%). (3): The velocities of 10 m s-1 to 16 m s-1 are suitable input rates from the point of view of turbulence intensity. (4): It is concluded that from the point of view of wear to the velocity of 10 to 16 m s-1, practical use is possible, and the velocity of 18 m s-1 and 20 m s-1 require the reinforcement of the relevant sections.

Emitter is the key component in drip irrigation system. It is necessary to have a comprehensive understanding of the flow mechanisms within drip irrigation emitters to design emitters that have a high performance. The use of Computational fluid dynamics ((CFD)) to research the flow characteristics is appropriate because the labyrinth flow path is narrow and its boundary is complex. In this study, the flow in labyrinth channels was simulated by using the method of Computational fluid dynamics ((CFD)) to calculate the distributions of pressure and velocity of the flow, and to calculate the relationship between pressure and rate of discharge for three sample of one type emitter. The emitters were destroyed and sizes of those channels were calculated by photography with Scanning Electronic Microscope (SEM). To calculate the relationship between pressure and rate of discharge as well as simulation of flow in emitters' channels, laminar flow model and turbulence model were applied. Verification of the results obtained from the (CFD) simulation was conducted in laboratory, according to the ISO9261 standard.The results of simulation for the labyrinth channel well matched the measured data in laboratory Computational fluid dynamics provides a promising tool to help in the design of labyrinth channels used in drip emitters.

Emitter is the key component in drip irrigation system; it is designed to let out the water in pipe to drop into the soil slowly and uniformly. Uniformity of emitter discharge is dependent on some parameters such as water temperature. Temperature variations influence water properties, especially viscosity. This may be a significant factor affecting flow through emitters. Field and laboratory study on this object is time-consuming and expensive. Computational fluid dynamics provides a promising tool to help in study of flow behavior of water passing through the channel of labyrinth. In this study, the flow in labyrinth channels was simulated by using the method of Computational fluid dynamics ((CFD)) to calculate temperature effect on emitter discharge for three sample of one type emitter. For this purpose, emitter discharge for the six pressures: 2, 4, 6.1, 9.2, 12.25 and 16.33 mH20 and six temperature: 5, 15, 20, 25, 35, 45 and 55oC was simulated. Samples were destroyed and longitudinal and latitudinal cuttings for the samples were obtained and sizes of the channels were calculated by photography with Scanning Electronic Microscope (SEM). To simulate pressures and temperature effect on rate of discharge using (CFD), laminar flow model and turbulence model was applied. Verification of Results showed that the simulated data had a good agreement with the experimental data and also emitter discharge is insensitive to temperature variations and (CFD) provides a promising tool to reduce the cost and time of study on emitters.

In this research, some more applicable ferrofluids are produced and their mechanical specifications are measured, experimentally. Also, their treatments in the ventilated cavity geometry are assessed numerically. The magnetite nanoparticles are produced by a chemical combination of Fe2+and Fe3+with NH3. In order to solve the nanoparticles in the new mediums, a proper coating is added to them. Then they are solved in kerosene, brake oil, hydraulic oil and motor oil with different particle fractures. A pressure-based procedure to solve Navier-stokes equations with finite volume formulation is developed to simulate a magnetic fluid in ventilated cavity geometry. One of the usages of this geometry is found in magnetic separation. The ventilated cavity geometry includes a square medium with one velocity inlet and one velocity outlet. In addition, a magnetic field due to a DC current carrying wire is employed on the geometry. The magnetic field intensities, its positions and ferrofluids’ mediums are changed. Then, the flow characteristics for each case are obtained to find the optimum situation for magnetic separation. Finally, the optimum situations for magnetic separation and for local cooling are obtained and the best ferrofluid is suggested for each application.