10/29/2022 0 Comments Eddy viscosity ratio external flow![]() After 50 iterations, the ATSU is turned off automatically. These steps may involve spikes in the convergence monitoring data at iterations 10, 20 and 50. Other steps are then taken to gradually arrive at the converged result. At iteration 10, a spike in the convergence monitoring data will appear for the k and epsilon equations. With this solution as an initial guess, the two-equation turbulence model is started. The algorithm starts by running 10 iterations using a constant eddy viscosity model, so the k and epsilon equations are not solved. This algorithm goes through a number of steps to obtain turbulent flow solutions. Likewise, laminar flows that are run with this model will produce similar results to a solution run as laminar.Īuto Startup controls the Automatic Turbulent Start-Up (ATSU) algorithm. High Reynolds flows that are run with the Low Reynolds turbulence model will generally produce the same solution as would the k-epsilon model. Because of this, the Intelligent Solution Control should be enabled (the switch is located in the Solution Control dialog launched from the Solve task dialog.) Likewise, analyses run with this model may take more iterations to reach a fully converged solution. Note that analyses run with this turbulence model may not be as stable as those run with the k-epsilon model. We recommend increasing the number of mesh enhancement layers to 5 (using the Mesh Enhancement controls on the Meshing dialog). Buoyancy-driven (natural convection) flows that are barely turbulent.īecause this turbulent model does not use wall functions, Mesh Enhancement should be always be enabled.These types of flows can be very unstable when run with k-epsilon. The jet is highly turbulent when it first enters the room, but the flow slows down considerably, and the Reynolds number drops. A high-speed jet entering a large room.Other flow situations that perform well with the Low Reynolds turbulent model include: Typical applications include pipe flows and external aerodynamic flow transitioning between laminar and turbulent, as well as flow situations that have both high speed and low speed areas. ![]() The Reynolds number of such flow is typically between 1,500 and 5,000. This model is well suited for low speed, turbulent flows. ![]()
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