The Numerical Investigation Of The Influence Of The Extra Strains Using RSM Model / Muhd Khairul Asyraf bin Shahari.

A thesis submitted to The Universiti Teknologi Brunei (UTB) in partial fulfillment of the requirements for the degree of Master of Science (MSc) in Mechanical Engineering.

ABSTRACT
As the title suggest, this thesis focuses on the influence of extra strains being numerically studied using Reynolds Stress Model (RSM). This is specifically investigating on turbulent flow traveling through a square sectioned U-bend of medium and strong curvature radius (stationary case) using (CFD) modeling known as ANSYS Workbench. This is done in order to fill in the void exist regarding information on the effects of complex strain fields through numerical approach. Many researchers have conducted study on the subject and developed ideas. They also carried out a number of experiments in order to gather information that would help them better grasp the subject. However, the validation data between experiment and numerical has always been a challenge for turbulent flow using Reynolds Averaged Navier Stokes (RANS) model. The goal of every numerical investigation when validating is common, to mimic the experiment data as closest as possible. This study then provides validation data of two different case running only (RSM) turbulence model. Case 1 for Re 100,000 about Rc/L equal to 0.65 and Case 2 for Re 56,690 about Rc/L = 3.357. Only after validation of existing model can investigation involving modification of current existing model or in a way evolving them to produce a better agreement of result can be started. This study provides reliable comparison of data with former (RSM) model and the strong curvature case able to provide better agreement with experiment data. Hereby, this project provides study on modification of RANS model specifically the Reynold stress model (RSM) of strong curvature case where altercations on its coefficients such as constant will be conducted. The coefficient's constant available will be altered in Fluent workbench's setup and simulated. Finding of this study is in investigating if result accuracy can possibly be influenced by the altercation of coefficient under certain range of value where most plot of streamwise velocity data and Reynold stresses as well as separation points compiled in this study proven the coefficient variables able to influence either by improving or degrading the result accuracy. Additional study is further done for medium curvature curve to investigate shift of numerical setup from 1 Order Upwind to 2nd Order Upwind, resulting failure in improvement of result accuracy or in providing significant changes.

Thesis (Degree) -Universiti Teknologi Brunei, 2022.