www.coria-cfd.fr - User contributions [en]

User:Chnafa

2013-06-18T13:10:58Z

Chnafa: /* Personal Information */

Welcome on {{BASEPAGENAME}}'s user page.

== Personal Information ==

[[File:Photo_cv_cchnafa.jpg‎|right|thumb|Christophe Chnafa]]

Christophe Chnafa 
PhD student @ I3M

Office: I3M/B. 9, room 202b 
email: cchnafa@math.univ-montp2.fr 
Tel: +33 (0)4 67 14 92 97

== Personal Webpage ==

http://www.math.univ-montp2.fr/~chnafa/

== Lab Address ==
I3M 
UMR CNRS 5149. CC 051 
Universite Montpellier II 
Place Eugene Bataillon 
34095 Montpellier 
Tel: +33 (0)4 67 14 35 57 
Fax: +33 (0)4 67 14 35 58

User:Chnafa

2013-06-18T13:09:02Z

Chnafa:

Welcome on {{BASEPAGENAME}}'s user page.

== Personal Information ==

[[File:Photo_cv_cchnafa.jpg‎|right|thumb|Christophe Chnafa]]

Christophe Chnafa 
CNRS PhD student @ I3M

Office: I3M/B. 9, room 202b 
email: cchnafa@math.univ-montp2.fr 
Tel: +33 (0)4 67 14 92 97

== Personal Webpage ==

http://www.math.univ-montp2.fr/~chnafa/

== Lab Address ==
I3M 
UMR CNRS 5149. CC 051 
Universite Montpellier II 
Place Eugene Bataillon 
34095 Montpellier 
Tel: +33 (0)4 67 14 35 57 
Fax: +33 (0)4 67 14 35 58

File:Photo cv cchnafa.jpg

2013-06-18T13:07:24Z

Chnafa: Cchnafa's picture

Cchnafa's picture

YALES2 Gallery

2013-01-24T18:06:51Z

Chnafa: /* Simulation of a cardiac cycle (Christophe Chnafa, Simon Mendez, Franck Nicoud) */

== Combustion ==

=== '''PRECCINSTA Burner''' ([[User:Moureauv|Vincent Moureau]]) ===

Direct Numerical Simulation of an aeronautical burner [http://dx.doi.org/10.1016/j.combustflame.2010.12.004]. The mesh features 2.6 billion tetrahedrons and a resolution of 100 microns.
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ PRECCINSTA burner with YALES2
|-
| [[File:PRECCINSTA_2634M_q_crit_persp.png|center|thumb|Iso-surface of the Q criterion for the isothermal case|250px]]
| [[File:PRECCINSTA_2634M_T_pub.png|center|thumb|Temperature field for the fully premixed reacting case|250px]]
| [[File:PRECCINSTA_2634M_Y_OH.png|center|thumb|OH radical field for the fully premixed reacting case|250px]]
|-
| colspan="2" |
{| style="margin: 10px;"
| {{#widget:YouTube|id=B8o9Sfdqhhg|width=500|height=350}}
|}
| [[File:Couverture CRAS calcul intensif.png|center|thumb|Couverture du Numéro Spécial Calcul Intensif des Comptes Rendus de Mécanique de l'académie des sciences]]
|}

=== '''KIAI burner''' ([[User:Moureauv|Vincent Moureau]])===
Large-Eddy Simulations of a swirl burner designed and operated at CORIA (J.P. Frenillot, G. Cabot, B. Renou, M. Boukhalfa).
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ KIAI burner with YALES2
|-
| [[File:KIAI_382M_U.png|center|thumb|Velocity field for the cold flow - 382M tetrahedrons|350px]]
| [[File:KIAI_382M_Q.png|center|thumb|Q-criterion for the cold flow - 382M tetrahedrons|350px]]
|}

== Aerodynamics ==

=== '''Formula One''' ([[User:Taieb|David Taieb]], [[User:Ribert|Guillaume Ribert]] & [[User:Moureauv|Vincent Moureau]]) ===

Computation of a Formula 1 meeting with the 2010 regulations.

The design is based on the 2008 car which was simulated with the Fluent software with less than one million cells.
The new car has the main features observed during the early part of F1 season, like the coca bottle shaped sidepods, the double-deck diffuser, the outer mirror disposition (forbidden by the FIA in the second part of the season), the three elements front wing.

The body of the car is discretized with 6.5mm element leading to 36 M cells in the computational domain.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Formula One with YALES2
|-
| [[File:F1_36M_streamtraces_1.png|center|thumb|Formula 1 with 36 Million cells - Streamlines|400px]]
| [[File:F1_36M_Q_3.png|center|thumb|Formula 1 with 36 Million cells - Iso-Q criterion|400px]]
|-
| align="center" | {{#widget:YouTube|id=hhB7zQuL2QA|width=400|height=300}}
| align="center" | {{#widget:YouTube|id=7cjpkt9zru0|width=400|height=300}}
|}

=== '''Interaction between two Le Mans Series prototypes''' ([[User:Taieb|David Taieb]], [[User:Ribert|Guillaume Ribert]] & [[User:Moureauv|Vincent Moureau]]) ===
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Interaction between two Le Mans Series prototypes with YALES2
|-
| [[File:LMS_U_stream_025.jpg|center|Instantaneous streamlines colored by velocity RMS.|400px]]
| [[File:LMS_up_pressure.jpg|centerContour of pressure on the upper bodywork.|400px]]
|-
| [[File:LMS_stream_Umean.jpg|center|Streamlines of averaged velocity colored by velocity RMS.|400px]]
| [[File:LMS_wake_DF.jpg|center|Longitudinal slice of instantaneous velocity and downforce on bodies.|400px]]
|}

== Heat transfers ==

=== '''T7.2 Blade''' ([[User:Maheu|Nicolas Maheu]])===
Large-Eddy Simulation of heat exchanges on a turbine blade.
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ T7.2 blade with YALES2
|-
| [[File:240M_isoQ175M_colorP_hd.png|center|thumb|T7.2 Blade - Iso-Q criterion - 240M tetrahedrons|400px]]
| [[File:240M_isoT325K_colorUmean_hd_legend.png|center|thumb|T7.2 Blade - Iso-T 325K - 240M tetrahedrons|400px]]
|-
| {{#widget:YouTube|id=vNJrAP9F_kU|width=400|height=300}}
| {{#widget:YouTube|id=iZWYfN4vDrQ|width=400|height=300}}
|}

== Two-phase flows ==

=== '''Triple disk injector''' ([[User:Moureauv|Vincent Moureau]]) ===

Computation of a Triple Disk injector (Grout et al 2007). The densities and viscosities are those of water and air at atmospheric pressure and temperature. The video on the left was performed with 203 million tets and the one on the right with 1.6 billion tets with a resolution of 2.5 microns.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Primary atomization with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=20Yr9eYIDFA|width=400|height=300}}
|{{#widget:YouTube|id=y9YfcKCFX0g|width=400|height=300}}
|}
|}

=== '''Pouring flow''' ([[User:Moureauv|Vincent Moureau]] and [http://cmes.colorado.edu/ Olivier Desjardins]) ===

Sample computation of a 2D two-phase flow with realistic properties for air and water to highlight the robustness of the method developed by Desjardins and Moureau at the 2010 CTR Summer Program.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Primary atomization with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=dPIfdasA2jw|width=400|height=300}}
|}
|}

=== '''Splashing''' ([[User:Moureauv|Vincent Moureau]]) ===

2D computation with YALES2 of a Lagrangian spray splashing on a wall and forming a film modeled with a level set and the Ghost Fluid Method. The grey particles and the grey film have the properties of water and the color represents the velocity magnitude in the gas. The Lagrangian particle are one-way coupled to the gas through drag for sake of simplicity.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Wall splashing with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=tzfz80irCLc|width=400|height=300}}
|}
|}

== Bio-mechanics from [http://ens.math.univ-montp2.fr/ I3M lab in Montpellier] ==

=== '''Simulation of a cardiac cycle''' ([[User:Chnafa|Christophe Chnafa]], [[User:Mendez|Simon Mendez]], [[User:Nicoud|Franck Nicoud]]) ===

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Cardiac cycle with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=1ze6ZxrSDHw|width=400|height=300}}
|}
|}
3D computation of a cardiac cycle with the Arbitrary-Lagrangian Eulerian solver of YALES2. This solver and the calculations were done in the I3M lab of the University of Montpellier by C. Chnafa, S. Mendez and F. Nicoud. The color in the movie represents the vorticity.

The grid on which the fluid problem is computed is extracted from 4D (3D + time) medical images from a patient. Ten 3D images are taken from different times during the heart cycle. A grid is extracted from one medical image using a segmentation protocol. Then, grid deformations are computed from the combination of an image registration algorithm and of interpolations process. Hence, boundary movements are extracted from medical images and applied as boundary conditions for the fluid problem, resulting in a patient-specific computation.
The spatial resolution is imposed to be close to 0.8 mm in all three spatial directions along the cycle, which yields grids of approximately three-million tetrahedral elements. Valves are modelled by immersed boundaries, and the heart is handled by a conformal mesh.

== Advanced numerics ==

=== '''Immersed boundaries on unstructured grids''' ([[User:Moureauv|Vincent Moureau]]) ===

On the left, 2D computation with YALES2 of the flow around two moving cylinders with an immersed boundary technique implemented for unstructured grids. The color represents the velocity magnitude. On the right, simulation of a stirred-tank reactor with YALES2. The mesh consists of 31 million tetrahedra. Simulation performed by V. Moureau from CORIA and N. Perret from Rhodia-Solvay.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Immersed boundaries with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=4s0iZwdQ1AU|width=400|height=300}}
|{{#widget:YouTube|id=VJUX4hv3pfA|width=400|height=300}}
|}
|}

=== '''Mesh deformation''' ([[User:Moureauv|Vincent Moureau]]) ===

Demonstration of 2D mesh deformation with YALES2. Only the velocity of boundaries is prescribed and the movement of the nodes is found by inverting an elliptic system. Edge swapping is also activated in this example.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Mesh deformation with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=riJM_NOeA_M|width=400|height=300}}
|}
|}

YALES2 Gallery

2013-01-24T18:03:42Z

Chnafa: /* Simulation of a cardiac cycle (Christophe Chnafa, Simon Mendez, Franck Nicoud) */

== Combustion ==

=== '''PRECCINSTA Burner''' ([[User:Moureauv|Vincent Moureau]]) ===

Direct Numerical Simulation of an aeronautical burner [http://dx.doi.org/10.1016/j.combustflame.2010.12.004]. The mesh features 2.6 billion tetrahedrons and a resolution of 100 microns.
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ PRECCINSTA burner with YALES2
|-
| [[File:PRECCINSTA_2634M_q_crit_persp.png|center|thumb|Iso-surface of the Q criterion for the isothermal case|250px]]
| [[File:PRECCINSTA_2634M_T_pub.png|center|thumb|Temperature field for the fully premixed reacting case|250px]]
| [[File:PRECCINSTA_2634M_Y_OH.png|center|thumb|OH radical field for the fully premixed reacting case|250px]]
|-
| colspan="2" |
{| style="margin: 10px;"
| {{#widget:YouTube|id=B8o9Sfdqhhg|width=500|height=350}}
|}
| [[File:Couverture CRAS calcul intensif.png|center|thumb|Couverture du Numéro Spécial Calcul Intensif des Comptes Rendus de Mécanique de l'académie des sciences]]
|}

=== '''KIAI burner''' ([[User:Moureauv|Vincent Moureau]])===
Large-Eddy Simulations of a swirl burner designed and operated at CORIA (J.P. Frenillot, G. Cabot, B. Renou, M. Boukhalfa).
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ KIAI burner with YALES2
|-
| [[File:KIAI_382M_U.png|center|thumb|Velocity field for the cold flow - 382M tetrahedrons|350px]]
| [[File:KIAI_382M_Q.png|center|thumb|Q-criterion for the cold flow - 382M tetrahedrons|350px]]
|}

== Aerodynamics ==

=== '''Formula One''' ([[User:Taieb|David Taieb]], [[User:Ribert|Guillaume Ribert]] & [[User:Moureauv|Vincent Moureau]]) ===

Computation of a Formula 1 meeting with the 2010 regulations.

The design is based on the 2008 car which was simulated with the Fluent software with less than one million cells.
The new car has the main features observed during the early part of F1 season, like the coca bottle shaped sidepods, the double-deck diffuser, the outer mirror disposition (forbidden by the FIA in the second part of the season), the three elements front wing.

The body of the car is discretized with 6.5mm element leading to 36 M cells in the computational domain.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Formula One with YALES2
|-
| [[File:F1_36M_streamtraces_1.png|center|thumb|Formula 1 with 36 Million cells - Streamlines|400px]]
| [[File:F1_36M_Q_3.png|center|thumb|Formula 1 with 36 Million cells - Iso-Q criterion|400px]]
|-
| align="center" | {{#widget:YouTube|id=hhB7zQuL2QA|width=400|height=300}}
| align="center" | {{#widget:YouTube|id=7cjpkt9zru0|width=400|height=300}}
|}

=== '''Interaction between two Le Mans Series prototypes''' ([[User:Taieb|David Taieb]], [[User:Ribert|Guillaume Ribert]] & [[User:Moureauv|Vincent Moureau]]) ===
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Interaction between two Le Mans Series prototypes with YALES2
|-
| [[File:LMS_U_stream_025.jpg|center|Instantaneous streamlines colored by velocity RMS.|400px]]
| [[File:LMS_up_pressure.jpg|centerContour of pressure on the upper bodywork.|400px]]
|-
| [[File:LMS_stream_Umean.jpg|center|Streamlines of averaged velocity colored by velocity RMS.|400px]]
| [[File:LMS_wake_DF.jpg|center|Longitudinal slice of instantaneous velocity and downforce on bodies.|400px]]
|}

== Heat transfers ==

=== '''T7.2 Blade''' ([[User:Maheu|Nicolas Maheu]])===
Large-Eddy Simulation of heat exchanges on a turbine blade.
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ T7.2 blade with YALES2
|-
| [[File:240M_isoQ175M_colorP_hd.png|center|thumb|T7.2 Blade - Iso-Q criterion - 240M tetrahedrons|400px]]
| [[File:240M_isoT325K_colorUmean_hd_legend.png|center|thumb|T7.2 Blade - Iso-T 325K - 240M tetrahedrons|400px]]
|-
| {{#widget:YouTube|id=vNJrAP9F_kU|width=400|height=300}}
| {{#widget:YouTube|id=iZWYfN4vDrQ|width=400|height=300}}
|}

== Two-phase flows ==

=== '''Triple disk injector''' ([[User:Moureauv|Vincent Moureau]]) ===

Computation of a Triple Disk injector (Grout et al 2007). The densities and viscosities are those of water and air at atmospheric pressure and temperature. The video on the left was performed with 203 million tets and the one on the right with 1.6 billion tets with a resolution of 2.5 microns.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Primary atomization with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=20Yr9eYIDFA|width=400|height=300}}
|{{#widget:YouTube|id=y9YfcKCFX0g|width=400|height=300}}
|}
|}

=== '''Pouring flow''' ([[User:Moureauv|Vincent Moureau]] and [http://cmes.colorado.edu/ Olivier Desjardins]) ===

Sample computation of a 2D two-phase flow with realistic properties for air and water to highlight the robustness of the method developed by Desjardins and Moureau at the 2010 CTR Summer Program.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Primary atomization with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=dPIfdasA2jw|width=400|height=300}}
|}
|}

=== '''Splashing''' ([[User:Moureauv|Vincent Moureau]]) ===

2D computation with YALES2 of a Lagrangian spray splashing on a wall and forming a film modeled with a level set and the Ghost Fluid Method. The grey particles and the grey film have the properties of water and the color represents the velocity magnitude in the gas. The Lagrangian particle are one-way coupled to the gas through drag for sake of simplicity.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Wall splashing with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=tzfz80irCLc|width=400|height=300}}
|}
|}

== Bio-mechanics from [http://ens.math.univ-montp2.fr/ I3M lab in Montpellier] ==

=== '''Simulation of a cardiac cycle''' ([[User:Chnafa|Christophe Chnafa]], [[User:Mendez|Simon Mendez]], [[User:Nicoud|Franck Nicoud]]) ===

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Cardiac cycle with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=1ze6ZxrSDHw|width=400|height=300}}
|}
|}
3D computation of a cardiac cycle with the Arbitrary-Lagrangian Eulerian solver of YALES2. This solver and the calculations were done in the I3M lab of the University of Montpellier by C. Chnafa, S. Mendez and F. Nicoud. The color in the movie represents the vorticity.

The grid on which the fluid problem is computed is extracted from 4D (3D + time) medical images from a patient. Ten 3D images are taken from different times during the heart cycle. A grid is extracted from one medical image using a segmentation protocol. Then, grid deformations are computed from the combination of an image registration algorithm and of interpolations process. Hence, boundary movements are extracted from medical images and applied as boundary conditions for the fluid problem, resulting in a patient-specific computation.
The spatial resolution is imposed to be close to 0.8 mm in all three spatial directions along the cycle, which yields grids of approximately three-million tetrahedral elements.

== Advanced numerics ==

=== '''Immersed boundaries on unstructured grids''' ([[User:Moureauv|Vincent Moureau]]) ===

On the left, 2D computation with YALES2 of the flow around two moving cylinders with an immersed boundary technique implemented for unstructured grids. The color represents the velocity magnitude. On the right, simulation of a stirred-tank reactor with YALES2. The mesh consists of 31 million tetrahedra. Simulation performed by V. Moureau from CORIA and N. Perret from Rhodia-Solvay.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Immersed boundaries with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=4s0iZwdQ1AU|width=400|height=300}}
|{{#widget:YouTube|id=VJUX4hv3pfA|width=400|height=300}}
|}
|}

=== '''Mesh deformation''' ([[User:Moureauv|Vincent Moureau]]) ===

Demonstration of 2D mesh deformation with YALES2. Only the velocity of boundaries is prescribed and the movement of the nodes is found by inverting an elliptic system. Edge swapping is also activated in this example.

{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Mesh deformation with YALES2
|-
|
{| style="margin: 10px;"
|{{#widget:YouTube|id=riJM_NOeA_M|width=400|height=300}}
|}
|}

File:Systole.png

2012-07-10T14:50:23Z

Chnafa: uploaded a new version of "File:Systole.png"