[Nek5000-users] What is the accuracy of the particle tracking?

[nek5000-users at lists.mcs.anl.gov]

Hello,

I need to track particles in flow field solutions, and I saw that 
NEK5000 has particle tracking capabilities.
I checked the basic online documentation and searched in the mailing 
list and I was not able to find a full description of the particle 
tracking algorithm.

So my questions are the following?
1) What is the time-accuracy of the particle tracking solver? I mean, do 
you use Runge-Kutta 4th order or equivalent?
I guess that your interpolation in space is very accurate, but 
time-accuracy matters a lot for estimating particle trajectories right.

2) Do you solve for particle dynamics equations or just for perfect tracers?
I mean, is the code prepared to solve dVp/dt=f(Xp,t) rather than Vp=Up?
(where Xp is the particle position, Vp is the particle velocity, Up is 
the fluid velocity at the particle position.)
A simple example is the typical aerosol particle equation: 
dVp/dt=-1/St(Vp-Up),
where St is the Stokes number.

3) In my case, I need to solve a bit more complicated equation (See Loth 
and Dorgan (2009) Environ Fluid Mech, 9, pp187-206),
where "additional" terms such as lift, added mass, fluid stress and 
particuarly 'history' terms are considered.
Are any of these "additional" terms considered in your current 
implementation?
If not, is the code flexible enough to implement these additional terms 
using the current code structure?

Many thanks.
Alexis Espinosa-Gayosso
University of Western Australia
PS. It is my first time using this list, and I did not know how to set a 
particular thread or even If this is the right email address to write.
PS2. I did not know either how to post to an existing thread. Can you 
tell me how?

-- 
Alexis Espinosa Gayosso
Graduate Research Assistant
Civil, Environmental and Mining Engineering and The UWA Oceans Institute
The University of Western Australia
M015, 35 Stirling Highway
Crawley, WA 6009
Australia

Tel: (+618) 6488-1689
Fax: (+618) 6488-1015
Email: Alexis.Espinosa-Gayosso at uwa.edu.au
Web: www2.sese.uwa.edu.au/~espinosa/