![]() Simulation domain solved on a single core (left), simulation domain solved on four cores in parallel (right). This speeds up the computation time.įor example, consider a 2D square domain as shown below:įigure 2: Geometric domain decomposition. This means that different parts of the simulation domain are allotted to different cores and each part is run simultaneously. ![]() One of the biggest advantages of using SimScale is that simulations are run in parallel. Adjustable runtime: It is the same setting as Runtime although the time step Delta t may be adjusted to match with the write interval.Hence, the specified interval will be in seconds of this CPU time. CPU time: It represents the amount of time for which the CPU is used to process instructions during the simulation run.Runtime: With Runtime, data can be written every specified interval seconds of simulated time.Specify an interval in seconds of this real time which will act as a gap between two successive writes. Clock time: Clock time means the actual time or real time.For example, A write interval value of 3 for a time step length Delta t of 2 seconds means that the results will be written every 3 x 2 = 6 seconds. Time step: Specify the number of time steps to be skipped between two successive writes of results.The frequency is specified under Write interval. Under Write control, the user can select different methods to specify the frequency with which the simulation results will be written. Alpha represents phase fraction and Max alpha co is the maximum allowable value of Courant number based on the velocity at the interface between two fluids. This setting is available only for the Multiphase analysis type. This setting is only available for transient simulations. This setting is important since it adds an additional control over the freedom of adjusting the time step that we set under Adjustable time step. This setting defines the maximum time step length that may not be exceeded during the simulation. In most cases, CFL value between 0.5-0.7 is considered to give the best results. When explicit time integration schemes are used, we recommend the CFL value to be lower than 1. The above expression says that the information from a given cell must propagate only to its immediate neighbor cell. Where \(C\) is the Courant number, \(U\) is the flow velocity at the cell, \(\Delta x\) is the cell length, and \(\Delta t\) is the time step. How to set the Time Step Delta T in Transient CFD Simulations? Maximal Courant numberĪccording to Courant-Friedrichs Lewy (CFL) condition\(^1\):
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