OpenFOAM Tutorial (Chpt 2 — Section 5): controlDict Explained | Time Control +Write Interval deltaT

The full tutorials with supporting Sim files, geometries, documents, and teacher support are placed at Udemy. Please refer there. The courses are really cheap compared to the efforts it took to create them, but if anyone needs to have it free, contact me and I will find a way. StarCCM Courses: https://www.udemy.com/course/star-ccm-expert-applications-vol-1-real-engineering/?referralCode=536C577A98868E316EC9 https://www.udemy.com/course/complete-cfd-simulation-in-starccm-advanced/?referralCode=C05897D188FB69CC8296 https://www.udemy.com/course/star-ccm-for-beginners-from-zero-to-your-first-simulation/?referralCode=EFAD8399E5FE89354471 Other courses we have: https://www.udemy.com/course/openfoam-for-beginners-from-installation-to-real-simulation/?referralCode=C9B5C2ACEDD226EAD49F https://www.udemy.com/course/solidworks-without-the-confusion-a-clear-beginner-course/?referralCode=04CC037F67BFD995F1EA https://www.udemy.com/user/sahar-rouzbahani-2/ In this section of **Chapter 2**, we learn how to use **system/controlDict** to control the most important runtime settings in OpenFOAM: ✅ simulation time setup ✅ time step size (**deltaT**) ✅ how often results are written to the time folders We open `controlDict`, confirm the solver is **icoFoam**, and then configure: * **startFrom / startTime** (where the run begins) * **stopAt / endTime** (where the run ends — here we run to **0.5 s**) * why the **0 folder** matters (it provides the initial fields when `startTime = 0`) * **deltaT = 0.005 s** (5 ms) and how to justify it using the **Courant number** * writing control: **writeControl** and **writeInterval** (e.g., write every **20 timesteps**) * **purgeWrite** to limit the number of saved time folders and keep your case clean * output settings (ASCII/binary, precision, compression, time format) * **runTimeModifiable = true** so the solver can re-read controlDict during the run Finally, we do a practical **Courant number estimate**: In the next section, we’ll move to **fvSchemes** and **fvSolution** to define discretization schemes and linear solver settings. OpenFOAM controlDict, icoFoam controlDict, startFrom startTime, stopAt endTime, deltaT OpenFOAM, writeControl writeInterval, purgeWrite OpenFOAM, #OpenFOAM #CFD #icoFoam #controlDict #CourantNumber #TimeStep #FluidDynamics #OpenSourceCFD #Engineering #BeginnerCFD