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 0 Introduction 3 Assumptions 3 Mesh and boundary conditions 3 Pressure variation 5 Behavior of Mach number along the pipe for the different cases 7 Behavior of velocity magnitude along the pipe for the different cases 8 Behavior of temperature variation along the pipe 11 References 13 Introduction The main aim of the paper is to be able to implement CFD by analyzing effects of changes in pressure, temperature changes, velocity and Mach number. The design of s-pipe requires assessment of pressure, temperature changes, velocity and Mach number on the individual pipes as well as on the pipeline bundle as a single object. Direct data related to such pipeline configurations is scarce; therefore, the pipeline is sometimes simplified to allow easier implementation. However the validity of the equivalent diameter design concept has not been adequately investigated. Assumptions The following are the assumption were considered in the analysis Two different fluids with different densities and viscosities in case were oil and water. The Mach number range is from 0.048753 to 0.54885 The velocity will be varied between 72 m/s and 186m/s, The two different inlet Pressure conditions considered in the case were 3366.02 and 7903.35Pa Two different Reynolds numbers Two different Inlet Mach numbers were 0.21 and 0.83 Mesh and boundary conditions The mesh that Boundary The initial conditions will be Pressure 7903.35pa and boundary condition 3066.82Pa Velocity will be 72,0,0 Mach number 0.21 The figure above shows that the mesh geometry of the pipe pressure is focused on the front part. This means other parts of the pipe are not under extensive pressure as front. Validation of the numerical model A s-pipe of Mach number 0.21 will be simulated to validate the numerical model of this study. At the same time a rectangle of 28 by 16 will be used that is divided by 24458 elements. There have been accurate analyses meant to figure out very well the structure of a bearing to provide frequencies that is the appropriate for the pipe. This is meant to reduce the various problems that do arise from the cylinders especially if they have been in use for a long time. During the calculation of the various frequencies used in the bearings, the calculations do require one to know some basic information that is typically known. For example, the typical information includes the Mach number, pressure ranges temperature ranges and velocity. Pressure variation The output below shows the pressure variation. From the output it can be noted there is will be an increase in pressure with the increasing distance past S-shape of the pipe up exit point. At entry point marks the start of a decrease in pressure towards the end of s-shape. This movement will then result into a vortex formation in in the pipe as can be seen from the diagram. The pressure will be highest at the exit point of the pipe. It was found from graph that stagnation pressure decreases as the distance between the entry and the s-shape decreases, while past the shape pressure increases. The two figures above the shows that the level of pressure varies as distance changes. The pressure range is from 0.85kPa to 0.92kPa for validated values. When there is a restriction to the flow of fluid, in the form of an orifice plate meter inserted at a particular cross section of the flow, this reduction of area affects the fluid flow parameters in significant manner. In a pipe having a fluid flow, the portion near the boundary surface, is affected since all fluids are practically not in viscid and hence the solid surface imparts a no-slip condition which in turn retards the smooth fluid flow giving rise to a slower moving boundary layer. When a flow enters a duct, a boundary layer is almost immediately formed circumferentially around the inner side of the duct wall. The core of the flow which is in viscid in relation to the walls is restricted from freely moving due to the growth of a viscous boundary layer. Behavior of Mach number along the pipe for the different cases The output for Mach number shown below are as result of simulation and do show large fluctuations. The initial condition Mach number is 0.21 and it is shown in the s-shape pipe below The output below shows behavior of Mach number along the pipe for the different cases. It has been observed that Mach number under s-shape is highest compared with horizontal flow. The highest estimated Mach number value achieved was, at s-shape. At horizontal flow, Mach number tends to be decreasing. The results had two major observations that as the Mach number increase the flow increase to certain level before exits and time varies to different sizes of mesh. Behavior of velocity magnitude along the pipe for the different cases Fluid flow can be characterized as steady or unsteady. When the flow is steady, the velocity of the fluid at any point is consent in time. The velocity is not necessarily the same everywhere, but at any particular point, the velocity of the fluid passing that point remains constant in time. The density and pressure of a steadily flowing fluid are also constant in time. The continuity equation relates the flow velocities of fluid at two different points, based on the change in cross- sectional area of the pipe. According to the continuity equation, the fluid must speed up as it enters a constriction and the slow down to its original speed when it leaves the constriction. Using energy ideas, we will show that the pressure of the fluid in the constriction (s-shape) cannot be the same as the pressure before or after the constriction (S-shape). For horizontal flow, the speed is higher where the pressure is lower. From the output below, it can be noted velocity is lower at start point before increasing. The frictional effect of turbulent conditions on the flow is often simulated through the Manning formula. For some cases this may not be important, but for other cases the simplifications may lead to significant errors in modeling system behavior. Thus the numerical solution provides values of the averaged velocity and longitudinal unit flow on a grid of points across the cross-section. When there exists a certain amount of velocity gradient in the transverse direction of flow, which is similar to the　case of a practical boundary layer that develops along a stationary boundary. The fluid flows in neat layers so that each small portion of fluid that passes a particular point follows the same path as every other portion of fluid that passes the same point. The path that the fluid follows, starting from any point, is called a streamline. The streamlines may curve and bend, but they cannot cross each other; if they did, the fluid would have to ‘decide’ which way to go when it gets to such a point. The direction of the fluid velocity at any point must be tangent to the streamline passing through that point The figures above the shows that the Velocity varies, the highest Velocity vector are185.88m/s. At low water volume fractions, the water in the pipes is entrained by the flowing oil. The oil wets thus the pipe and the corrosion brought about by the water, given its containment of dissolved gases like CO2 or H2S, is small and unnoticeable. As the volume fraction of the water increases, the water break-out can appear. The bottom of the pipe is wetted by the water, and the corrosion begins. Given the effects of water corrosion on the oil field as well as the frequency of it, it is not surprising to observe the great amount of research produced about the subject as well as the number of experimental models and methods developed to measure the amount of water corrosion and at which levels of the water cut it occurs. Initial models were flawed by their underestimation of the critical velocity for high water cuts as they were more suitable for low water volume fraction. Later studies and experimental models have attempted to measure the conditions that lead to water entrainment by the flowing oil more precisely. An example of this is Smith et. al 1987 who pointed out that oil can carry up to 20% water at velocities larger than 1m.s-1. Behavior of temperature variation along the pipe The change in temperature will be analyzed using output below for s-shape pipe. Looking at it; it was observed that there was a sudden increase and decrease in the temperature at s-shape area as compared to horizontal point. The main reason of the sudden increase was because of velocity slow due to shape. Conclusion The flow representation must be nonlinear and viscous. The model must be able to cope with flow separation and re-attachment. The unsteadiness due to the model must be included but the analysis is not straightforward because of input data erroneous. Finally, it must be stressed that the computational requirement for such a calculation is very considerable since a time-accurate, steadiness analysis must be undertaken for a s-shape flow. The simulated model water levels are plotted on assumed data to obtain result. References References McGraw-Hill Companies. (2005). Boundary-layer flow. McGraw-Hill Concise Encyclopedia of Physics (5th ed.). The McGraw-Hill Companies, Inc. Spink, L. K. (1967). Principles and Practice of Flow-meter Engineering. The Foxboro Company. Foxboro, MA. Read More