I Declare That, • the Work in This Degree Thesis Is Completely My
Total Page：16
File Type：pdf, Size：1020Kb
2 ESEIAAT I declare that, • The work in this Degree Thesis is completely my own work, • No part of this Degree Thesis is taken from other people’s work without giving them credit, all references have been clearly cited, • I’m authorised to make use of the research group related information I’m providing in this document. • I understand that an infringement of this declaration leaves me subject to the foreseen disciplinary actions by The Universitat Politècnica de Catalunya - BarcelonaTECH. Santiago Guarner Escribano 30/06/2020 ___________________ __________________ ___________ Student Name Signature Date Title of the Thesis : Study of fluid-dynamics applications by using on-web-browser software._________________________________________________________ ________________________________________________________________ __________________________________________________ BACHELOR’S THESIS AEROSPACE TECHNOLOGY ENGINEERING ACADEMIC YEAR: 2019-2020 Q2 Study of fluid-dynamics applications by using on-web-browser software Guarner Escribano, Santiago Director: Prof. Pedro Javier Gamez Montero Co-director: Prof. Roberto Castilla July 2020 Abstract This thesis provides an introduction to computational fluid dynamic using on-web-browser soft- ware. Therefore, it presented two classical cases so that the students apply the theory learned in the lessons and, also, an investigation has been done in order to optimize the meshing procedure with SimScale. In addition to this, in the last part of the project, the learner is introduced to the compressible flow and it is described the problems found with the software and some solutions. The two cases are the Pipe Flow and the Flat Plate Flow. Every time, it has been imperative to fol- low the typical procedure; pre-processing, simulation and post-processing in order to underline to the learner the importance of the interpretation of the results and the sensitivity of the simulations. Bachelor’s Thesis Contents 1 Introduction7 1.1 Aim of the Project..............................7 1.2 Project requirements............................7 1.3 Scope of the project.............................7 1.4 Justification and Utility...........................8 1.5 State of the Art...............................9 1.6 About SimScale............................... 11 2 Introduction to SimScale 12 2.1 Turbulence Models............................. 12 2.1.1 K-Epsilon Standard Turbulence Model.............. 12 2.1.2 K-Omega Standard Turbulence Model............... 12 2.1.3 K-Omega SST Turbulence Model................. 13 2.2 The Lid-Driven Cavity Case........................ 14 2.2.1 The mesh of the case........................ 15 2.2.2 The Selection of the Solver..................... 16 2.2.3 2.3 The Topological Entities and Regions............. 16 2.2.4 The Fluid.............................. 17 2.2.5 The Boundary Conditions..................... 18 2.2.6 Setting-up the Case......................... 21 2.2.7 Running the Simulation...................... 22 2.2.8 Post-processing........................... 23 3 Internal Flow 27 3.1 Theoretical Framework........................... 27 3.2 Meshing Methods.............................. 30 3.3 Pipe Flow Case Study............................ 30 3.3.1 Analytical results.......................... 31 3.3.2 Laminar Flow............................ 31 3.3.3 Post-processing with ParaView................... 38 3.3.4 Turbulent Flow........................... 46 3.3.5 Post-processing with ParaView................... 51 3.3.6 Numerical Results......................... 58 4 External Flow 62 4.1 Theoretical Framework........................... 62 4.2 Meshing Methods.............................. 64 4.3 Flat Plate Case Study............................ 64 4.3.1 Analytical Results......................... 64 4.3.2 SimScale Tutorial.......................... 65 4.3.3 Post-processing........................... 70 4.3.4 Numerical Results......................... 73 5 Compressible Flow 80 5.1 The Nozzle Compressible Flow: Problems and Solutions......... 80 3/102 Bachelor’s Thesis 6 Environmental Impact 88 6.1 Environmental Impact from the Study and the Document Synthesis.... 88 7 Budget 89 8 Planing and Scheduling 91 9 Conclusions and Further Investigation 93 9.1 Target - Achievement Synthesis...................... 94 Annex 95 A Wall Functions 95 A.1 What are wall functions........................... 95 B Solvers and CFL Condition 96 B.1 CFL Condition............................... 96 B.2 Simscale Solvers.............................. 97 References 100 4/102 Bachelor’s Thesis List of Figures 3.1 Typical velocity and shear t distributions in turbulent flow near a wall: (a) shear; (b) velocity. [4]............................ 27 3.2 u+ over y+. [4]............................... 28 3.3 Developing velocity profiles and pressure changes in the entrance of a duct flow. [4]................................ 29 3.29 Pressure distribution of a laminar flow over the central line......... 42 3.36 Velocity profile at the exit of the pipe for the laminar flow......... 46 3.50 Pressure distribution of a Turbulent flow over the central line........ 52 3.51 Velocity profile at the exit of the pipe for the Turbulent flow........ 52 3.62 Shear stresses at the exit of the pipe for a turbulent flow over y+ with the refined boundary layer mesh......................... 57 3.63 Shear stresses at the exit of the pipe for a turbulent flow over y with the refined boundary layer mesh......................... 57 3.65 u+ over y+ at the exit of the pipe for the refined boundary layer mesh... 58 3.66 Pressure distribution with a linear regression of the fully laminar devel- oped flow points............................... 59 3.67 Velocity profile at different positions along the pipe............. 59 3.68 Pressure distribution of a turbulent flow for an homogeneous mesh..... 60 3.69 Velocity profile at the exit of a turbulent flow for an homogeneous mesh.. 60 3.70 Transition from small cells to bigger at the refined mesh.......... 60 3.71 Pressure perturbations caused by a bad transition.............. 60 3.72 Shear stresses for a turbulent flow for an homogeneous mesh........ 61 3.73 u+ over y+ at the exit for a turbulent flow for an homogeneous mesh.... 61 4.1 The variation of the local friction coefficient for flow over a flat plate [3]. 62 4.14 Laminar velocity profile configuration.................... 70 4.17 Laminar boundary layer........................... 71 4.18 Laminar Shear stress over the plate..................... 72 4.19 u+ vs y+ at the end of a flat plate, laminar flow............... 72 4.20 Velocity profile at a flat plate, v = 2 m/s................... 73 4.21 Mesh computation test............................ 74 4.22 Bad velocity profile.............................. 74 4.23 Boundary layer at a flat plate, v = 2 m/s................... 74 4.24 Shear stress over a flat plate, v = 2 m/s.................... 75 4.25 u+ vs y+ at the end of a flat plate, v = 2 m/s................. 75 4.26 Velocity profile at a flat plate, turbulent flow................. 76 4.27 Boundary layer at a flat plate, turbulent flow................. 76 4.28 Shear stress over a flat plate, turbulent flow................. 77 4.29 u+ vs y+ at the end of a flat plate, turbulent flow.............. 77 4.30 Comparison of dimensionless laminar and turbulent flat-plate velocity profiles at the end of the plate with the profiles from[4]........... 78 4.31 Drag coefficient of laminar and turbulent boundary layers on smooth and rough flat plates[4].............................. 79 5.1 Homogeneous with hexahedral cells mesh.................. 81 5.2 Error for the first compressible run...................... 81 5/102 Bachelor’s Thesis 5.3 Residuals for a compressible run....................... 82 5.4 Nonphysical numerical compressible results................. 82 5.5 Pressure distribution, Pinlet = 1:5e5 Pa.................... 83 5.6 Velocity distribution, Pinlet = 1:5e5 Pa.................... 83 5.7 Mesh computed for the new geometry.................... 84 5.8 Residuals, Pinlet = 5e5 Pa.......................... 84 5.9 Pressure distribution............................. 84 5.10 Velocity distribution, Pinlet = 5e5 Pa and Tinlet = 1000 k.......... 85 5.11 Pressure distribution............................. 85 5.12 Residuals with a ramped pressure inlet, Pinlet = 2:1e5 Pa and Poutlet = 5e4 Pa....................................... 86 5.13 Residuals for the under-relaxed simulation................. 87 5.14 Residuals for the under-relaxed simulation and the relative tolerance re- duced..................................... 87 List of Tables 1 Data of the problem. *The two values of the velocity are for the turbulent and laminar regime, respectively....................... 31 2 Analytical results for a laminar flow..................... 31 3 Analytical results for a turbulent flow.................... 31 4 Data of the problem, flat plate. *The three values of the velocity/Reynolds number are for the turbulent, transient and laminar regime, respectively.. 64 5 Theoretical average friction coefficient for inlet velocities of 1, 2 and 10 m/s, respectively............................... 64 6 Average friction coefficient from the simulation for inlet velocities of 1, 2 and 10 m/s, respectively........................... 78 7 CO2 emissions from the energetic consumption............... 88 8 Direct costs.................................. 89 9 Indirect costs................................. 89 10 Personal working hours breakdown..................... 90 11 Hours week breakdown........................... 91 12 SimScale’s available solvers