Freezing the flow field or energy field temporarily deactivates their associated equation solvers during the simulation of the current step. Deactivating these equations allows the app to dedicate computing power to solving other physics and can reduce the simulation's run time. You can freeze the flow field (that is, the pressure and momentum equations) when you have already solved the flow solution, either from the initial conditions or from the solution of a previous step. You can freeze the energy field (that is, the energy equation) if you enabled thermal effects in the fluid physics options. There are many examples of when it is appropriate to use expert cycle controls. For example, you can freeze the flow field when simulating a pathogen that an HVAC system transports within a building over time. The flow field in this example is the building HVAC system, because the HVAC system controls the pressure and momentum of the airflow. You can first use a steady-state step to calculate the physics of the steady airflow within the building. You can then use a transient flow step, with the flow field frozen, to calculate the physics of the pathogen's transport within the building over time. While the app expends a substantial amount of computational power when solving the steady-state step, it expends less computational power when solving the transient flow step. Less computational power is required when solving the transient flow step because the app does not solve for the pressure and momentum of the airflow. Since these properties are independent of time, it is not worth running and rerunning the transient flow step with their equations active, because their solutions never change. Instead, you can rerun simulations of the transient flow step to solve for other important physics related to the pathogen's transport. Your pressure and momentum results remain accessible from the steady-state step. | |||||||||