Spikes occurs in data plots

zhuzhangkr · January 20, 2016, 03:51

Hi, everyone!

Recently i'm solving a wedge dropping problem. i applied overset mesh technique and DFBI module to simulate the drop motion of wedge body in a computational domain...

However, when checking my result plots, i found some spikes in my pressure results... it means, there are some results are extremely high or low.. For example, the pressure at first time step could be as high as 2kPa... horrible!
BTW, i give the wedge body an initial velocity of 3 m/s... so i guess something wrong at discrete momentum eq. or divergence or somewhere..

some numerical conditions: segregated implicit flow... VOF method... laminar... no-slip B.C..

This's reaaaally a headache problem i can't explain...

Is there anyone who know this?? Really appreciate it!!

fluid23 · January 20, 2016, 12:01

are your time steps converging?

fluid23 · January 20, 2016, 12:02

and is the time step size appropriate?

zhuzhangkr · January 20, 2016, 22:36

Quote:

Originally Posted by MBdonCFD

and is the time step size appropriate?

Thanks for response!

My time step is 1e-5 s... in order to keep Convective Courant Number under 1.0 during whole simulation... Unsteady condition is selected therefore time step is fixed during computation..

January 20, 2016, 03:51	Spikes occurs in data plots	#1
zhuzhangkr New Member zhu zhang Join Date: Jul 2015 Posts: 5 Rep Power: 11	Hi, everyone! Recently i'm solving a wedge dropping problem. i applied overset mesh technique and DFBI module to simulate the drop motion of wedge body in a computational domain... However, when checking my result plots, i found some spikes in my pressure results... it means, there are some results are extremely high or low.. For example, the pressure at first time step could be as high as 2kPa... horrible! BTW, i give the wedge body an initial velocity of 3 m/s... so i guess something wrong at discrete momentum eq. or divergence or somewhere.. some numerical conditions: segregated implicit flow... VOF method... laminar... no-slip B.C.. This's reaaaally a headache problem i can't explain... Is there anyone who know this?? Really appreciate it!!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
How to setup a simple OpenFOAM cluster?	TommiPLaiho	OpenFOAM Installation	3	October 27, 2013 16:15
export data at nodes	Meenu	FLUENT	1	December 30, 2011 02:24
matching variable data with grid point data	anfho	OpenFOAM Programming & Development	0	May 6, 2011 16:28
drawing of contour plots	chinthakindi	Main CFD Forum	1	April 27, 2004 05:33
make an animation plots from the data	colopolo	Main CFD Forum	4	September 30, 2003 11:45

January 20, 2016, 12:01		#2
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 18	are your time steps converging?

January 20, 2016, 12:02		#3
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 18	and is the time step size appropriate?