REE 470-06 CFD Setting Up Physics (1) PDF

6- CFD Setting Up Physics Module: Computer-aided Design and Engineering (REE470) Associate Professors: Mohammed Ali Abdelnaby Fall 2024 Lecture Outline Recall (Convergence, Mesh Independence Study and Validation) Introduction Material Properties Cell Zone Conditions Boundary Conditions...

6- CFD Setting Up Physics Module: Computer-aided Design and Engineering (REE470) Associate Professors: Mohammed Ali Abdelnaby Fall 2024 Lecture Outline Recall (Convergence, Mesh Independence Study and Validation) Introduction Material Properties Cell Zone Conditions Boundary Conditions Mesh Interfaces Summary  Convergence, Mesh Independence Study and Validation It is important to remember that your solution is the numerical solution to the problem that you posed by defining your mesh and boundary conditions. The more accurate your mesh and boundary conditions, the more accurate your "converged" solution will be. https://www.computationalfluiddynamics.com.au/convergence-and-mesh-independent-study/ Bladeless wind turbine Difference in the mass flow rate at inlets and outlets Vortex shedding (unsteady analysis) Convergence, Mesh Independence Study and Validation Convergence, Mesh Independence Study and Validation Convergence, Mesh Independence Study At this point, you need to compare the monitor point and Validation values from Step 2 against those from Step 1. If they are the same (within your allowable tolerance, say 5%), then the mesh at Step 1 was accurate enough to capture the result. If the value at Step 2 is not within acceptable values of the Step 1 result, then this means that your solution is changing because of your mesh resolution, and hence the solution is not yet independent of the mesh. In this case you will need to move to Step 3. In general, we prefer to have 3 levels of mesh. Convergence, Mesh Independence Study and Validation Convergence, Mesh Independence Study and Validation Convergence, Mesh Independence Study and Validation https://www.grc.nasa.gov/WWW/wind/valid/tutorial/valassess.html Large eddies account for the majority of momentum transfer and turbulent mixing and contain the majority of the turbulent energy. Large Eddies Simulation (LES) is more accurate than the RANS (Reynolds Average Navier-Stocks Simulation) because it directly and fully captures these eddies, while the RANS approach models them. Introduction  To make our CFD CLOs software- ANSYS Fluent Workflow independent and professionally use ANSYS and COMSOL Last lectures and When Practice Starting for Today We will discuss the items in the same arranged order in COMSOL as much as possible Setting Up Physics: Other Group Boxes We will discuss this in Lecture 8 (solving) Setting Up Physics: Create/Edit Materials Fluid Density Operating Pressure Compressible flow (P = 0) In compressible flow (P =101325 Pa) Cell Zones and Boundary Zones Setting Up Physics: Cell Zones Setting Up Physics: Cell Zones Setting Up Physics: Boundaries You can change BCs after mesh generation except Periodic BCs Defining Boundary Conditions Available Boundary Condition Types General Guidelines for Boundaries in CFD Symmetry Planes Geometry and Flow Symmetry Geometry Symmetry only Specifying Well Posed Boundary Conditions We will recall some tips on slide # 35 (for writing and reading reports) Specifying Well Posed Boundary Conditions Specifying Well Posed Boundary Conditions No change at the outlet No change at the outlet Specifying Well Posed Boundary Conditions Domain independent results Periodic Boundary Condition Summary Appendix (TIPS & TRICKS) Appendix: Options for Defining Common Properties Case Setup Replication All settings are the same, but I want to replace the mesh Cell Zone Definition –Fluid Cell Zones Definition –Solid Profile Data and Solution Data Interpolation (Recall Slide#24)  Profile Boundary Conditions Select Profiles in the Boundary Conditions panel (left figure) After reading the profile, open the panel for the boundary where it is to be applied Select the arrow and scroll down in the drop-down list until the desired profile is reached (right figure)–The first three items in the list will usually be the coordinates of the profile variables –do not select these Profiles can be created from experimental data by creating an appropriately formatted file–The file format details are in the User’s Guide Boundary Zone: Velocity Inlet Boundary Zone: Pressure Inlet M: Mack No K: Sp. heat ratio Boundary Zone: Mass Flow Inlet  The same properties at the outlet Boundary Zone: Pressure Outlet Fully Developed Profile Turbulent 10*D (entrance length) (Specially 1 inlet and 1 outlet) Laminar 0.05*Re (entrance length) Boundary Zone: Outflow If you don’t know the flow properties at the single exit the outflow is recommended If you don’t know the mass flow rate percentage at the multiple exits: the outflow is not recommended 0.333 0.333 0.333 Modelling Multiple Exits Boundary Zone: Wall Moving wall-like lid cavity TUTORIAL Axis Boundaries Other Inlet / Outlet Boundary Conditions Periodic Boundaries Internal Face Boundaries Specifying Well Posed Boundary Conditions Renewable Energy Program Zewail City THANK YOU