Ecfd:ecfd 7th edition - Revision history

Benard: /* Turbulence - P. Benard, CORIA & L. Bricteux, UMONS */

2024-03-06T09:26:01Z

‎Turbulence - P. Benard, CORIA & L. Bricteux, UMONS

Benard: /* Numerics - S. Mendez, IMAG & G. Balarac, LEGI */

2024-03-06T09:17:25Z

‎Numerics - S. Mendez, IMAG & G. Balarac, LEGI

Balarac: /* T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran) */

2024-02-21T16:08:52Z

‎T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran)

Balarac: /* = P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) */

2024-02-21T06:43:41Z

‎= P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG)

Nicoud: /* = P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) */

2024-02-16T11:05:22Z

‎= P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG)

Nicoud: /* = P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) */

2024-02-16T11:04:18Z

‎= P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG)

Nicoud: /* P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) */

2024-02-16T10:59:33Z

‎P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG)

Dillon: /* C3: Dynamic sub-grid-scale wrinkling for diffusion flames - S. Dillon (EM2C/Safran), R. Mercier (Safran), E. Espada, B. Fiorina, D. Veynante (EM2C) */

2024-02-16T09:17:58Z

‎C3: Dynamic sub-grid-scale wrinkling for diffusion flames - S. Dillon (EM2C/Safran), R. Mercier (Safran), E. Espada, B. Fiorina, D. Veynante (EM2C)

Dillon: /* Combustion - K. Bioche, CORIA & R. Mercier, Safran */

2024-02-16T09:17:12Z

‎Combustion - K. Bioche, CORIA & R. Mercier, Safran

Balarac: /* M3: Anisotropic mesh refinement - R. Barbera (LEGI & Safran), G. Ghigliotti, G. Balarac (LEGI), R. Letournel (Safran) */

2024-02-15T10:33:02Z

‎M3: Anisotropic mesh refinement - R. Barbera (LEGI & Safran), G. Ghigliotti, G. Balarac (LEGI), R. Letournel (Safran)

← Older revision		Revision as of 09:26, 6 March 2024
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	==== T6: Development of coupling between YALES2-OpenFAST – A. Parinam (TUDelft/CORIA), P. Benard (CORIA), F. Houtin-Mongrolle (SGRE) ====		==== T6: Development of coupling between YALES2-OpenFAST – A. Parinam (TUDelft/CORIA), P. Benard (CORIA), F. Houtin-Mongrolle (SGRE) ====
		+	Aero-servo-elastic engineering solvers, commonly used in the wind energy industry for structural response and power assessments, are unsuited for wake simulations, as aerodynamic loads are usually derived from a BEM-like method. To tackle this, the target is to couple the YALES2 library to OpenFAST, an NREL code for wind turbines, in the same way as the already existing YALES2-BHawC coupling.
		+	An external coupling library has been created, linking the YALES2 and OpenFAST libraries and enabling the exchange of information between the data structures of each code. This data exchange has been tested and validated during the ECFD7. The next steps rely on exchanging the proper data during the actuator line tilmestep and further validate the coupling.

	==== T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran) ====		==== T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran) ====

← Older revision		Revision as of 09:17, 6 March 2024
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	[1] ''Toward the use of LES for industrial complex geometries. Part II: Reduce the time-to-solution by using a linearised implicit time advancement, Berthelon et al., JoT, 2023''		[1] ''Toward the use of LES for industrial complex geometries. Part II: Reduce the time-to-solution by using a linearised implicit time advancement, Berthelon et al., JoT, 2023''
		+
		+	==== N3: Parallelisation of Actuator Line Method - H. Mulakaloori (CORIA), P. Benard (CORIA), F. Houtin-Mongrolle (SGRE) ====
		+
		+	The implementation of the Actuator Line Method (ALM) into the YALES2 library leads to poor performances when many wind turbine rotors are set. Indeed, each rotor object is a derived type treated sequentially by all the processors participating to the computation. With 30 turbines in a computation, the return time is increased by 70% while the arithmetic intensity appears to be low. The objective of this sub-project is to improve the computation performances of the ALM already identified: (i) Assign one MPI communicator by rotor object gathering the processors close to the turbine and set-up a master/slave processus by communicator. This will allow the simultaneous rotors computation and reduce the number of MPI exchanges. (ii) Work on the domain decomposition to limit the number of processors attributed to each turbine. This would reduce or even eliminate MPI communications.

	==== N4: Non-uniform outlet pressure and coupling with CWIPI - J. B. Lagaert (LMO), Y. Lakrifi, T. Berthelon, G.Balarac (LEGI) , R. Letournel (Safran) ====		==== N4: Non-uniform outlet pressure and coupling with CWIPI - J. B. Lagaert (LMO), Y. Lakrifi, T. Berthelon, G.Balarac (LEGI) , R. Letournel (Safran) ====

← Older revision		Revision as of 16:08, 21 February 2024
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	==== T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran) ====		==== T7: Confidence intervals for estimators – C. Papagiannis, G.Balarac (LEGI), R. Letournel (Safran) ====
		+
		+	The inference of statistics for the results of LES requires quantifying the quality of the estimates from the available sample. In the case of CFD the sample is the number of measurements of a QoI and is very closely connected to the simulation's time step. Since our computational resources are finite, the sampling error of the estimates will never vanish. The purpose of this project is to provide Confidence Intervals (CI) to the inferred statistics so the user can have an indicator of the quality level of the simulation 'on-the-fly'. This requires the calculation of the autocorrelation of the collected samples, to correct the estimated sample variance used for the CI. This was achieved through a ''selective autocorrelation function estimator'' that also takes into account the non-constant time steps. With this we calculated sample-size independent confidence intervals that provide the corrected variance, compared to a naive estimation of the sample variance that assumed the samples as fully uncorrelated. With this we pave the way for having a universal estimator for the autocorrelation of some QoI, that incorporates autocorrelations and cross-correlations with the time-step.

	=== Two Phase Flow - M. Cailler, Safran & V. Moureau, CORIA ===		=== Two Phase Flow - M. Cailler, Safran & V. Moureau, CORIA ===

@@ Line 174: / Line 174: @@
 Medical devices in contact with blood (e.g. artificial valves) are used to treat various cardiovascular diseases, but their thrombogenicity remains the main unresolved issue in their development. A numerical model of blood platelets is being constructed to help to understand the effect of microstructuration on the thrombogenicity of artificial surface. The Force Coupling Method (FCM) was previously implemented and allows the modelisation of ellipsoidal particle and their interaction with the surrounding fluid. During the workshop, the particle model was extended to include adhesive and repulsive interactions with walls or with other particles. The adhesive bonds are modeled with springs forming when the distance between a node of a particle surface and a node of the wall or another particle is smaller than a given threshold. The stiffness of the bond is increased after a given formation time to mimic the 2-step adhesion process of platelets to von Willebrand Factor. A Lennard-Jones potential was used to model the collision of particles. Future work will aim at generalizing these implementations for an arbitrary number of particles (currently only working for 2 particles) and ensuring the interactions are unaltered by the crossing of a periodic boundary.
-==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ===
+==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ====
 Under certain circumstances, platelets do not bind to the surface but to a specific protein called Willebrand factor, which has the unique property of unfolding once subjected to a sufficiently high shear flow. The aim of this project was to investigate how to represent this mechanism within the YALES2 framework. During ECFD7, the immersed-boundary methodology already used to treat thin membranes (such as the red blood cell membrane) was extended to cover 1D elements evolving in a 3D flow. Preliminary tests have been successfully carried out, notably on a embedded beam immersed in shear flow, showing the potential of this approach to include another ingredient relevant to thrombosis modeling. Future work will include adding a repulsive force to avoid non-physical binding, as well as carrying out simulations involving Willebrand factor, platelets and red blood cells.

← Older revision		Revision as of 11:05, 16 February 2024
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	==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ===		==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ===
		+
		+	Under certain circumstances, platelets do not bind to the surface but to a specific protein called Willebrand factor, which has the unique property of unfolding once subjected to a sufficiently high shear flow. The aim of this project was to investigate how to represent this mechanism within the YALES2 framework. During ECFD7, the immersed-boundary methodology already used to treat thin membranes (such as the red blood cell membrane) was extended to cover 1D elements evolving in a 3D flow. Preliminary tests have been successfully carried out, notably on a embedded beam immersed in shear flow, showing the potential of this approach to include another ingredient relevant to thrombosis modeling. Future work will include adding a repulsive force to avoid non-physical binding, as well as carrying out simulations involving Willebrand factor, platelets and red blood cells.

	==== P5: Towards even more efficient particle algorithms - M. Helal (CORIA/Safran), M. Cailler (Safran) ====		==== P5: Towards even more efficient particle algorithms - M. Helal (CORIA/Safran), M. Cailler (Safran) ====

← Older revision		Revision as of 11:04, 16 February 2024
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	==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ===		==== P4: vWF Unfolding - C. Raveleau, S. Mendez, F. Nicoud (IMAG) ===
−	Under certain circumstances, platelets do not bind to the surface but to a specific protein called Willebrand factor, which has the unique property of unfolding once subjected to a sufficiently high shear flow. The aim of this project was to investigate how to represent this mechanism within the YALES2 framework. During ECFD7, the immersed-boundary methodology already used to treat thin membranes (such as the red blood cell membrane) was extended to cover 1D elements evolving in a 3D flow. Preliminary tests have been successfully carried out, notably on a embedded beam immersed in shear flow, showing the potential of this approach to include another ingredient relevant to thrombosis modeling. Future work will include adding a repulsive force to avoid non-physical binding, as well as carrying out simulations involving Willebrand factor, platelets and red blood cells.

	==== P5: Towards even more efficient particle algorithms - M. Helal (CORIA/Safran), M. Cailler (Safran) ====		==== P5: Towards even more efficient particle algorithms - M. Helal (CORIA/Safran), M. Cailler (Safran) ====

@@ Line 203: / Line 203: @@
 To reduce the expensive computational cost of Plasma-Assisted Combustion (PAC) full 3D simulations, the EM2C laboratory has developed phenomenological approaches to model Nanosecond Repetitively Pulsed (NRP) plasma discharges in reacting flows (Castela 2016 & Blanchard 2023). As part of previous works and ECFDs, both models were implemented and validated in the Low-Mach number framework (YALES2-VDS). While they were also implemented in the Compressible framework (YALES2-ECS), the validation against existing measurements or computations remained. During the workshop, numerical simulations of pin-to-pin configurations were performed with different numerical schemes and reactive mixtures to validate both models in ECS. The energy deposition was relatively well-validated through 2D simulations in the conditions of Castela et al. CNF 2016 and Rusterholtz et al. JPhysD 2013. A glimpse of baroclinic instabilities was observed through 3D simulations in the conditions of Castela et al. PROCI 2017.
-==== C3: Dynamic sub-grid-scale wrinkling for diffusion flames - S. Dillon (EM2C/Safran), R. Mercier (Safran), E. Espada, B. Fiorina, D. Veynante (EM2C) ====
+==== C3: Dynamic sub-grid-scale wrinkling model for diffusion flames - S. Dillon (EM2C/Safran), R. Mercier (Safran), E. Espada, B. Fiorina, D. Veynante (EM2C) ====
 Large-eddy-simulation (LES) of reactive flows is widely used in both academic and industrial applications. Combustion phenomena occur at a scale often smaller than the LES mesh size, therefore, turbulent combustion models are required to account for unresolved turbulent flame interactions. The modeling of sub-grid-scale (SGS) flame turbulence interactions can be described with a flame surface wrinkling factor which measures the ratio of the total flame surface area to the resolved flame surface area. Flame surface wrinkling models are often expressed by assuming equilibrium between turbulent motions and flame surface wrinkling, however, in realistic burners non-equilibrium is present and dynamic models are needed to adapt model parameters. Fractal-like models require information about the outer and inner cut-off length scales along with a fractal exponent, which is determined dynamically from resolved scales in the LES. The dynamic formalism can be coupled with the Filtered Tabulated Chemistry for LES (F-TACLES) model, where the required cut-off length scales are tabulated in the F-TACLES table along with other filtered thermochemical variables. The coupling of the F-TACLES model with the dynamic formalism has been previously applied to premixed flames in the past, however, the formal extension to non-premixed flames has never been investigated. The objective of this project is to investigate the performance of the dynamic SGS flame surface wrinkling model coupled with the F-TACLES model for non-premixed flames. A priori tests are conducted on a 2D H2/Air reactive mixing layer and HYLON, a 3D turbulent dual-swirl coaxial H2/Air injector. In both 2D and 3D cases, the modelled flame surface density shows good agreement with the filtered flame surface density extracted from the DNS. Moreover, the variation of the fractal model exponent in the HYLON test case is significant, highlighting the importance of the dynamic procedure. A posteriori tests were also conducted, and modelled chemical reaction rates show promising results.

← Older revision		Revision as of 09:17, 16 February 2024
Line 202:		Line 202:

	To reduce the expensive computational cost of Plasma-Assisted Combustion (PAC) full 3D simulations, the EM2C laboratory has developed phenomenological approaches to model Nanosecond Repetitively Pulsed (NRP) plasma discharges in reacting flows (Castela 2016 & Blanchard 2023). As part of previous works and ECFDs, both models were implemented and validated in the Low-Mach number framework (YALES2-VDS). While they were also implemented in the Compressible framework (YALES2-ECS), the validation against existing measurements or computations remained. During the workshop, numerical simulations of pin-to-pin configurations were performed with different numerical schemes and reactive mixtures to validate both models in ECS. The energy deposition was relatively well-validated through 2D simulations in the conditions of Castela et al. CNF 2016 and Rusterholtz et al. JPhysD 2013. A glimpse of baroclinic instabilities was observed through 3D simulations in the conditions of Castela et al. PROCI 2017.		To reduce the expensive computational cost of Plasma-Assisted Combustion (PAC) full 3D simulations, the EM2C laboratory has developed phenomenological approaches to model Nanosecond Repetitively Pulsed (NRP) plasma discharges in reacting flows (Castela 2016 & Blanchard 2023). As part of previous works and ECFDs, both models were implemented and validated in the Low-Mach number framework (YALES2-VDS). While they were also implemented in the Compressible framework (YALES2-ECS), the validation against existing measurements or computations remained. During the workshop, numerical simulations of pin-to-pin configurations were performed with different numerical schemes and reactive mixtures to validate both models in ECS. The energy deposition was relatively well-validated through 2D simulations in the conditions of Castela et al. CNF 2016 and Rusterholtz et al. JPhysD 2013. A glimpse of baroclinic instabilities was observed through 3D simulations in the conditions of Castela et al. PROCI 2017.
		+
		+	==== C3: Dynamic sub-grid-scale wrinkling for diffusion flames - S. Dillon (EM2C/Safran), R. Mercier (Safran), E. Espada, B. Fiorina, D. Veynante (EM2C) ====
		+
		+	Large-eddy-simulation (LES) of reactive flows is widely used in both academic and industrial applications. Combustion phenomena occur at a scale often smaller than the LES mesh size, therefore, turbulent combustion models are required to account for unresolved turbulent flame interactions. The modeling of sub-grid-scale (SGS) flame turbulence interactions can be described with a flame surface wrinkling factor which measures the ratio of the total flame surface area to the resolved flame surface area. Flame surface wrinkling models are often expressed by assuming equilibrium between turbulent motions and flame surface wrinkling, however, in realistic burners non-equilibrium is present and dynamic models are needed to adapt model parameters. Fractal-like models require information about the outer and inner cut-off length scales along with a fractal exponent, which is determined dynamically from resolved scales in the LES. The dynamic formalism can be coupled with the Filtered Tabulated Chemistry for LES (F-TACLES) model, where the required cut-off length scales are tabulated in the F-TACLES table along with other filtered thermochemical variables. The coupling of the F-TACLES model with the dynamic formalism has been previously applied to premixed flames in the past, however, the formal extension to non-premixed flames has never been investigated. The objective of this project is to investigate the performance of the dynamic SGS flame surface wrinkling model coupled with the F-TACLES model for non-premixed flames. A priori tests are conducted on a 2D H2/Air reactive mixing layer and HYLON, a 3D turbulent dual-swirl coaxial H2/Air injector. In both 2D and 3D cases, the modelled flame surface density shows good agreement with the filtered flame surface density extracted from the DNS. Moreover, the variation of the fractal model exponent in the HYLON test case is significant, highlighting the importance of the dynamic procedure. A posteriori tests were also conducted, and modelled chemical reaction rates show promising results.

	==== C4: Developement of an automated virtual scheme generator for CFD - T. Luu, M. Hustache, N. Darabiha, B. Fiorina (EM2C) ====		==== C4: Developement of an automated virtual scheme generator for CFD - T. Luu, M. Hustache, N. Darabiha, B. Fiorina (EM2C) ====

@@ Line 65: / Line 65: @@
 Mesh adaptation is a crucial tool in order to automate industrial RANS numerical simulations. To meet this need, we need to carry out mesh adaptation as quickly as possible by setting up an efficient, parallel solution. To this end, we have explored two avenues: a parallel edge-splitting algorithm that has recently been initiated in the ParaDiGM library, and a solution based on [https://github.com/nasa/refine the refine library] for adapting meshes with MPI implementation. On the one hand, we fixed several bugs in our split operator, and validated it on test cases of increasing complexity with a node-centered solver. In addition, we've added interfaces to refine so as to avoid using files, and call directly in library mode. We also investigated geometric projection issues during the mesh adaptation procedure, notably by looking at solutions such as EGADS, which offers a simplified API for CAD interrogation. We finally implemented metric gradation (in serial), metric intersection and complexity computations. All the ingredients we've tested give us a clearer picture of the entire mesh adaptation process.
-==== M3: Anisotropic mesh refinement - R. Barbera (LEGI & Safran), G. Ghigliotti, G. Balarac (LEGI), R. Letournel (Safran) ====
+==== M3: Anisotropic mesh refinement - R. Barbera (LEGI/Safran), G. Ghigliotti, G. Balarac (LEGI), R. Letournel (Safran) ====
 Mesh adaptation is now a key feature for simulations of complex industrial flows. For transient flows such as multiphase and/or reactive flows, where regions of interest are strongly moving in space, dynamic mesh adaptation appears as the most suitable strategy. This strategy is now widely used in YALES2 based on isotropic mesh definition. The purpose of this project is to adapt this strategy to an anisotropic framework to reduce the overall simulation costs (in term of memory consumption, cpu cost and time to solution). In order to be able to handle multiphase flows, the main objective of the project is to study the conditions for accurately describing the dynamics of the level-set function with an anisotropic mesh. Accuracy is mainly assessed in terms of interface position and mass conservation. The inaccuracy of mass conservation is mainly due to interpolation errors after the adaptation step. Furthermore, inaccuracy in interface position may be due to misalignment between the anisotropic mesh elements and the interface normal. The first methodological corrections have been proposed, as an adaptation of the level-set reinitialization algorithm to the anisotropic mesh.