Implementation of Computational Fluids Dynamics - Lab Report Example

Implementation of Computational fluids Dynamics Implementation of Computational fluids Dynamics Customer Inserts His/Her Name Customer Inserts Grade Course Customer Inserts Tutor’s Name 27, 05, 2017 Table of Contents Introduction 3 Assumptions 3 Mesh 3 Numerical calculation 4 Pressure variation 5 Behavior of velocity magnitude along the pipe for the different cases 9 Behavior of temperature variation along the pipe 13 References 14 Introduction The main aim of the project was to carry out computerized fluid dynamics of s-shaped pipe in terms of its behavior when pressure, temperature, velocity, Mach number and change of density and velocity used. The analysis will be a 3D dynamics simulation and the result will be recorded in form screen shorts and graphs. The result will be compared the conclusion will be made Assumptions The following are the assumption will considered The fluids that will be used is water and oil The Mach number range is from 0.048753 to 0.54885 The velocity will be varied between 17 m/s AND 186m/s, Pressure ranges pressure range is from 0.80kPa to 0.95kPa The length of pipe considered is 0.1 to 0.7m Mesh In 2D analysis mesh will chosen for fluid flow as well as the pipe the selected mesh for the pipe is square and its shown below .It can be noted that it has many cells. Geometry The mesh geometry of the pipe to be used is shown below that is the front part of the pipe. The main reason for considering the front part of the pipe is that it receives the fluid first. If it is in terms of the temperature it will receive the highest / coldest temperature first. The geometry will guide the flow of the liquid. That’s why we have divergent geometry of the flow environment at the front. The boundary layer formed in the pipe contained for vortices that is feed into the shear layer when water is flowing. The geometry figure is shown below. Numerical calculation In the case at hand, Euler-Bernoulli Beam Theorem will be used in deriving a solution for the flow of the liquid within the s section of the pipe. The following formula is adopted in demining the boundary conditions of the flow. the boundary conditions for the equation are , Then the natural frequency will be , and . When and Pressure variation The pressure was varied between 0.8kPa to 0.95kPa. This was done by varying the streamline of the liquid into the pipe. Once the liquid is in the pipe at the entry point and the pressure is exerted the direction of the liquid will not change. The direction at any given point is always tangent to the streamline of the liquid passing at that point. The figure below shows the impact of changes in pressure against the distance covered. The intention is to show how varying pressure will be affected by the distance covered. From the graph it can be noted that the pressure increases as the distance increases. It can be noted that the relationship between pressure and distance is positive and as distance increases pressure increases this findings are critical to the management of the piping system. From the figure the lowest entry pressure was 0.85Kpa and the largest entry pressure is 0.85kPa. it will be noted that pressure increased to 0.915kPa at 0.35m from the entry this can be explained using the rolls of pressure.. Since the discharge of flow is dependent on velocity of the flow, which in turn is dependent on the pressure head differences, results obtained using the distance within the pipe. It can be noted that pressure results is not the same as they produced by different models to calculate values .The distance to be covered during the flow is important in design the system as this will enable one understand the minimum flow capability. The rate of flow of fluid will be affected by static pressure in the pipeline that is conveying the fluid. The pick-up velocity of the fluid is critical in the analysis of the system as it will determine the amount of fluid to be conveyed. The figure below shows flow and column From the graph above it can be noted that pressure is formed on the plains of the pipes because the liquid is moving at a constant velocity and at constant time. according to the graph pressure increases with the increase in distance to a certain level where it is constant. pressure uses Bernoulli’s equation which relates to pressure flow and gradient. Bernoulli’s equation P1 +pgy1+ ½ pv21=p2+pgy2+ ½ pv22 (or p+Pgy+ ½ Pv2 = Constant) Behavior of Mach number along the pipe for the different cases The plot below shows behavior of Mach number along the pipe for the different cases. It can be noted that Mach number increases along the distance. For these values of Re, the boundary layer over the cylinder surface will separate due to the adverse pressure gradient imposed by the divergent geometry of the flow environment at the rear side of the cylinder, leading to formation of a shear layer. The boundary layer formed along the cylinder contains a considerable amount of vorticity that is fed into the shear layer formed downstream of the separation point and causes the shear layer to roll up into a vortex with a sign identical to that of the incoming vorticity from the graph it can be noted that the Mach number ranges from 0.048753 to 0.54885. the mach number is the highest at the entry point of pipe while at the internal surface of the pipe the mach number is the lowest especially at the bed bend. It can also be noted that the mach number is uniform at the section where the pipe is straight. From this observation it can be noted that the mach number is influenced by the shape of the pipe and the gradient of the ground. it goes without saying that mach number depends with shape and gradient. Transporters of liquid using the pipeline ought to understand this fact that, as it plays a very important role in ensuring there is no breakage of pipes in the way. varying the mach number was meant to give results that can be used to reduce problems that are associated with piping. Some of the major significance of this study focuses on, is the interaction between fluid and a structure, which occurs when fluid causes deformation of a structure. This deformation causes changes in boundary conditions in fluid flow. Two-dimensional simulations at low Reynolds number, as a first approximation to the problem, can be used to give some insight about the details of the vortex dynamics in the wake and vortex impingement occurring when the cylinders are arranged in a tandem configuration.. The attraction of applying numerical methods to such problems is that the flow can be studied in closer detail. Behavior of velocity magnitude along the pipe for the different cases Thevelocityofthefluid flowinthepipewassimulated basedonthepressuredifferencesalong pipe.Theresultingobservationswereeffectivelyplottedthetransversevelocityprofileoftheflowregimeinsidetheductandtheairvelocityateachpointofthecrosssectionwascalculated.Andforselected dischargesthus calculated,thelongitudinalpressureprofilewasalsographicallyplotted.The two figures shows The velocity profile at Position 1 is almost the same spread around the entire cross section. The big fluctuation and vagaries from a strict average value for velocity at Position 1 could be due to the fact that since it is nearer to the inlet, there could be a lot external influences that causes slight changes in pressure head, thereby fluctuating the velocity of the flow. From the graph5 below it can stated that the pattern of the plotted points on the graph slopes from right to left of the scatter plot suggesting a positive relationship between the two variables. This kind of findings simply goes with the general expectation. The finding through the scatter diagram is further reinforced by the value of the correlation coefficient between the two variables under consideration. The positive sign of the coefficient indicates a positive relationship while the very low absolute value of the coefficient, 0.001, simply implies minimum relationship. The figures above the shows that the Velocity varies, the highest Velocity vector are185.88m/s. The minimum picked up velocity in the pipeline approximately 17.035 m/s, which if the velocity along the pipeline less than 6 m/s, it will be blockage. In the entrance of stepped pipeline, internal diameter of pipeline has raised and it causes by the velocity are drop slightly to 118.34m/s due to change in diameter size. Again after this point the velocity to be dramatically increase to 185.88m/s at the bend of pipeline The path that the inlet air follows, starting from point of entry, is called a streamline. The streamlines curves and bends, but they cannot cross each other; if they did, the fluid will change direction. The direction of the air velocity at any point must be tangent to the streamline passing through that point. Thevelocityprofileis thus constrainedtoano-growthconditionandfullydevelops only ftertraversingdownstream.. The fully developed fluid flow would either be laminar or turbulent and would be validated by the Reynolds number calculated for the velocity at a particular cross section under review. Theoretically, in a transverse velocity profile, the velocity nearer to the walls is lesser than the high velocity at the center, supported by the fact that a boundary layer is formed. Behavior of temperature variation along the pipe To test the impact of temperature, temperatures of 300k and 350 were used. the screen short below shows where temperature was high as well as low. the temperature was highest at the entry point as well as the exit point of the bend. However it was lowest at the surface near the bend. this can be explained by the fact that there is high energy while liquid is entering the bend at he same time there is high energy when it is living. Blowing affects both dynamical and thermal boundary layers, leading to increased thickness and decreased gradients by injecting some low-momentum low-temperature fluid. This translates to reduced transfer coefficients, and lower shear stress and convective heat flux, allowing for low viscous drag and an efficient thermal protection when cold fluid is blown and keeping the surface temperature at an appropriate level. In addition to this, there is an increase in both pressure drag and overall drag. The blowing affects the near wake, leading to decreased vortex shedding frequency because of slower wake dynamics and a larger formation region. The pressure field is linked to the vortex shedding frequency. The pressure defect at the back of the cylinder tends to “fill up” with blowing, leading to lower transverse static pressure gradients in the near wake. This implies that complete blowing is of interest to the wake control (vibrations, suppression of the shedding), the thermal protection (aircraft engine blades) or for the reduction of the viscous drag The wide fluctuations in temperature would be alluding to the turbulence, or a phase of transition to turbulence flow property inside the pipe. Further to that, the fact that the friction factors of the pipe causes a marginal energy loss and thus a reduced pressure head difference could I turn be a limiting factor to properly evaluate the data and understand the flow process. References Eleni, D. C., Athanasios, T. I. &Dionissios, M. P., 2011. Evaluation of the turbulence models for the simulation of the flow over a National Advisory Committee for Aeronautics (NACA) 0012 airfoil. Journal of Mechanical Engineering Research Sahul, N. K. & Imam, S. 2015.Analysis of Transonic Flow over an Airfoil NACA0012 using CFD.International Journal of Innovative Science, Engineering & Technology, Zhao, M., Cheng, L., & Teng, B., 2007, Numerical Modeling of Flow and Hydrodynamic Forces around a Piggyback Pipeline near the Seabed, Journal of Waterway, Port, Coastal, and Ocean Engineering , pp.286-294. Read More