{"id":359040,"date":"2024-03-26T12:52:44","date_gmt":"2024-03-26T12:52:44","guid":{"rendered":"\/forum\/forums\/topic\/convergence-varying-radial-velocity-and-timestep-size-in-a-simulation\/"},"modified":"2024-03-26T19:35:53","modified_gmt":"2024-03-26T19:35:53","slug":"convergence-varying-radial-velocity-and-timestep-size-in-a-simulation","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-varying-radial-velocity-and-timestep-size-in-a-simulation\/","title":{"rendered":"Convergence varying radial velocity and timestep size in a simulation"},"content":{"rendered":"<p>Hi,&nbsp;<\/p>\n<p>Transient simulation a rotating container with fluid inside.<\/p>\n<p>The radial velocity is constant for a period of time after which I am attempting to simulate a near step change in the radial velocity (0.25s decceleration to 0 [rad\/s]).&nbsp;<\/p>\n<p>To decrease simulation time I want to<\/p>\n<ul>\n<li>Have a larger timestep and less max iterations per timestep for a period before the change in radial velocity<\/li>\n<li>Decrease the timestep size and increase the max iterations per timestep during the decelleration period<\/li>\n<li>Return to the original timestep and max iterations per timestep for the remainder of the simulation.&nbsp;<\/li>\n<\/ul>\n<p>I created an expression that follows the desired radial velocity profile using conditional statements.<\/p>\n<p>My question is, if I were to stop the simulation before the decelleration period, restart with a much lower timestep value and increased iterations per timestep will this affect my simulations convergence? and similarly after the decelleration period, will the abrupt increase in timestep size again affect convergence?&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>Thanks in advance,<\/p>\n","protected":false},"template":"","class_list":["post-359040","topic","type-topic","status-closed","hentry","topic-tag-fluent-ansys-1","topic-tag-fluent-cfd-ansys-1","topic-tag-convergence","topic-tag-iterations","topic-tag-rotation","topic-tag-time-step","topic-tag-transient"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hi, Transient simulation a rotating container with fluid inside.The radial velocity is constant for a period of time after which I am attempting to simulate a near step change in the radial velocity (0.25s decceleration to 0 [rad\/s]). 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