Why Is The Time-Step Important For Fluid Dynamics? | FEniCS CFD

In this video, we will have a look at why the time-step is so important in computational fluid dynamics (CFD) problems. Also, we look at a method to automate the time-step using the Courant–Friedrichs–Lewy (CFL) condition. The time-step is very important in how we solve partial differential equations (PDE) at each step. Changing the time-step can change how large an assumption we make over the time-step period. The larger the assumption, the less likely dynamics will model the true, real-world dynamics (assuming realistic parameters are used). Additionally, other factors can affect the time-step size such as the solver and solver iterations. Also, we look at a method to automate the time-step using the Courant–Friedrichs–Lewy (CFL) condition. The CFL condition provides a maximum time-step value based on the distance between mesh cells and maximum velocity within the CFD problem. This provides the basis for automating the time-step for Navier-Stokes problems going forward in BERNAISE, Binary ElectRohydrodyNAmIc SolvEr, using FEniCS back-end for solving partial differential equations. All free and open-source running in Python. However, why does it not always work? Read more here: https://nanomedic.org/why-is-the-time... Love this content - Like, Subscribe and let me know in the comments! Notice a problem or mistake? (I am human) Please let me know politely in the comments below! Thanks for watching. Subscribe: https://bit.ly/3MIKQv2 Check out the code used here: https://github.com/MattH688/BERNAISE CAD to mesh wiki: https://github.com/MattH688/BERNAISE/... CFD visualisation was done using Paraview: https://www.paraview.org/ Music is HTML by Riot provided by the YouTube Audio Library Free Music. --------------Contents of this video-------------- 00:00 - Intro 00:30 - Time-Steps General Rule Of Thumb 00:50 - Why reducing a Time-Step can be bad 01:05 - Automating the Time-Step (Courant–Friedrichs–Lewy (CFL) Condition) 01:33 - Re-arranging the CFL Condition to calculate the maximum time-step 01:49 - What can go wrong with large time-steps 02:13 - Why CFL can produce the wrong time-step 02:44 - What the CFL can be used for 03:10 - Other factors affecting the time-step size #CFD #CFL #timestep