optiflow

Optiflow is an implementation of a shape-optimization method for two-dimensional incompressible flows.

Installation

You will need a recent FreeFem++ installation, see http://www.freefem.org/ff++/. This program was written and tested with FreeFem++ 3.42 and should work properly with any subsequent version.
Download the zip archive at https://github.com/flomnes/optiflow/archive/master.zip or clone this repository
```
git clone https://github.com/flomnes/optiflow.git
```
then navigate to the decompressed directory :
```
cd optiflow-master
```
or
```
cd optiflow
```

Usage

Five examples can be found in the file run_case.sh. The general syntax is

FreeFem++-nw main.edp [--config numconfig] [--resu resfolder] [numerical parameters]

The basic options are:

--config	configuration number, from 1 to 5
--resu		folder in which the files and results will be saved, created if non-existent

Numerical paramters:

--navsto	1=Navier-Stokes, 0=Stokes
--raffinit	required edge size when remeshing : hmax=raffinit, hmin=raffinit/sqrt(2)
--optraff	1=remesh if necessary, 0=no remeshing
--minarea	remesh if any element has an area less than minarea
--binit		initial value for b
--btarget	final value for b : b is no longer updated if b >= btarget
--tau		value of tau, step of the gradient method
--l0		initial value of the Lagrange multiplier
--gamma		value of the regularization parameter
--jjmax		maximal number of outer iterations
--errc		value for the stopping criterion \eps_{stop} on the residual
--beta		0 for perimeter constraint, 1 for volume constraint (default)
--delta		Select the functional : 0 for the dissipated energy, 1 for the least-square profile at the outlet
--cv		Ratio (required constraint value)/(initial constraint value). 1 for an identical initial and required volume or perimeter
--alpha		Update ratio for b : b^{n+1}=alpha*b^n
--save		1=save all figures in the result directory, 0=save nothing at all
--saveevery n	figures will be saved every n iterations

Notes

If gnuplot is installed, you can plot relevant data from a result directory. Simply copy plot.gp from the project root the result directory and execute gnuplot plot.gp. A file called "multi.pdf" will be generated.
Crashes may occur for because of mesh self-intersections. You may try to choose a smaller value for tau. You can also increase the value of minarea so that remeshing will be done earlier.

Authors & contributors

optiflow has been developped by Florian Omnès (Université Pierre et Marie-Curie), Yannick Privat (Université Pierre et Marie Curie, CNRS), Charles Dapogny (Université Grenobles-Alpes, CNRS) and Pascal Frey (Université Pierre et Marie Curie, Institut du Calcul et des Données)
Anyone wishing to contribute is welcome

License

optiflow is licensed under the terms of the LGPL (LICENSE.md)