How to approach CFD simulation results of the flow past a cylinder?

Ashkan Kashani · February 26, 2021, 18:03

Hi all,
I'm doing a transient simulation of flow past a rectangular cylinder close to the free surface. As far as I'm concerned, the common practice is to discard the initial stages of the transient solution up to some point that a so-called statistically stationary state is supposed to have reached. Then the solution should proceed with a time resolution much finer than the vortex shedding dominant period in order to ensure accuracy. From this point on, flow properties are captured over an interval sufficiently long to realize statistical convergence of the results.
In the literature, the above has often been implemented in a subjective manner, mainly through visual examination of the results. No quantitative information exists on how to ensure a statistically stationary state holds.
I'm wondering if there are more standard objective methods of determining the portion of the data to be discarded, and the appropriate time step and time duration to use in the simulation.
I appreciate any comments.

aero_head · February 27, 2021, 13:09

Hello Ashkan,

I am investigating a similar simulation. Looking through this thread helped me a lot: time step and vortex shedding frequency

I found the information to be quite accurate.

isabellone · March 3, 2021, 10:10

I'm doing a transient simulation of flow past a rectangular cylinder close to the free surface. As far as I'm concerned, the common practice is to discard the initial stages of the transient solution up to some point that a so-called statistically stationary state is believed to have reached. Then the solution should proceed with a time resolution much finer than the vortex shedding dominant period in order to ensure accuracy. From this point on, flow properties are captured over an interval sufficiently long to realize statistical convergence of the results. forpc.onl jiofi.local.html

nerdvid · February 7, 2022, 03:46

In the present work, an in-house UnSteady Double Wake Model (USDWM) is developed for simulating general flow problems behind bodies. The model is presented and used to simulate flows past a circular cylinder at subcritical, supercritical, and transcritical flows. vidmate instagram video download

February 26, 2021, 18:03	How to approach CFD simulation results of the flow past a cylinder?	#1
Ashkan Kashani Member Ashkan Kashani Join Date: Apr 2016 Posts: 46 Rep Power: 10	Hi all, I'm doing a transient simulation of flow past a rectangular cylinder close to the free surface. As far as I'm concerned, the common practice is to discard the initial stages of the transient solution up to some point that a so-called statistically stationary state is supposed to have reached. Then the solution should proceed with a time resolution much finer than the vortex shedding dominant period in order to ensure accuracy. From this point on, flow properties are captured over an interval sufficiently long to realize statistical convergence of the results. In the literature, the above has often been implemented in a subjective manner, mainly through visual examination of the results. No quantitative information exists on how to ensure a statistically stationary state holds. I'm wondering if there are more standard objective methods of determining the portion of the data to be discarded, and the appropriate time step and time duration to use in the simulation. I appreciate any comments.

March 3, 2021, 10:10		#3
isabellone New Member Carlton Flores Join Date: Mar 2021 Posts: 1 Rep Power: 0	I'm doing a transient simulation of flow past a rectangular cylinder close to the free surface. As far as I'm concerned, the common practice is to discard the initial stages of the transient solution up to some point that a so-called statistically stationary state is believed to have reached. Then the solution should proceed with a time resolution much finer than the vortex shedding dominant period in order to ensure accuracy. From this point on, flow properties are captured over an interval sufficiently long to realize statistical convergence of the results. forpc.onl jiofi.local.html Last edited by isabellone; March 6, 2021 at 06:38.

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February 27, 2021, 13:09		#2
aero_head Senior Member Kira Join Date: Nov 2020 Location: Canada Posts: 435 Rep Power: 9	Hello Ashkan, I am investigating a similar simulation. Looking through this thread helped me a lot: time step and vortex shedding frequency I found the information to be quite accurate.

February 7, 2022, 03:46		#4
nerdvid New Member cartlon flores Join Date: Feb 2022 Posts: 1 Rep Power: 0	In the present work, an in-house UnSteady Double Wake Model (USDWM) is developed for simulating general flow problems behind bodies. The model is presented and used to simulate flows past a circular cylinder at subcritical, supercritical, and transcritical flows. vidmate instagram video download