SAM
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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 22 Feb 2024 01:27:29 GMT2024-02-22T01:27:29ZAn a posteriori-implicit turbulent model with automatic dissipation adjustment for Large Eddy Simulation of compressible flows
http://hdl.handle.net/10985/18002
An a posteriori-implicit turbulent model with automatic dissipation adjustment for Large Eddy Simulation of compressible flows
NOGUEIRA, Xesús; RAMÍREZ, Luis; FERNÁNDEZ-FIDALGO, Javier; DELIGANT, Michael; KHELLADI, Sofiane; CHASSAING, Jean-Camille; NAVARRINA, Fermín
In this work we present an a posteriori high-order finite volume scheme for the computation of compressible turbulent flows. An automatic dissipation adjustment (ADA) method is combined with the a posteriori paradigm, in order to obtain an implicit subgrid scale model and preserve the stability of the numerical method. Thus, the numerical scheme is designed to increase the dissipation in the control volumes where the flow is under-resolved, and to decrease the dissipation in those cells where there is excessive dissipation. This is achieved by adding a multiplicative factor to the dissipative part of the numerical flux. In order to keep the stability of the numerical scheme, the a posteriori approach is used. It allows to increase the dissipation quickly in cells near shocks if required, ensuring the stability of the scheme. Some numerical tests are performed to highlight the accuracy and robustness of the proposed numerical scheme.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/180022020-01-01T00:00:00ZNOGUEIRA, XesúsRAMÍREZ, LuisFERNÁNDEZ-FIDALGO, JavierDELIGANT, MichaelKHELLADI, SofianeCHASSAING, Jean-CamilleNAVARRINA, FermínIn this work we present an a posteriori high-order finite volume scheme for the computation of compressible turbulent flows. An automatic dissipation adjustment (ADA) method is combined with the a posteriori paradigm, in order to obtain an implicit subgrid scale model and preserve the stability of the numerical method. Thus, the numerical scheme is designed to increase the dissipation in the control volumes where the flow is under-resolved, and to decrease the dissipation in those cells where there is excessive dissipation. This is achieved by adding a multiplicative factor to the dissipative part of the numerical flux. In order to keep the stability of the numerical scheme, the a posteriori approach is used. It allows to increase the dissipation quickly in cells near shocks if required, ensuring the stability of the scheme. Some numerical tests are performed to highlight the accuracy and robustness of the proposed numerical scheme.A Higher-Order Chimera Method for Finite Volume Schemes
http://hdl.handle.net/10985/18046
A Higher-Order Chimera Method for Finite Volume Schemes
RAMÍREZ, Luis; NOGUEIRA, Xesús; OURO, Pablo; NAVARRINA, Fermín; KHELLADI, Sofiane; COLOMINAS, Ignasi
In this work a higher-order accurate finite volume method for the resolution of the Euler/Navier–Stokes equations using Chimera grid techniques is presented. The formulation is based on the use of Moving Least Squares approximations in order to obtain higher-order accurate reconstruction and connectivity between the overlapped grids. The accuracy and performance of the proposed methodology is demonstrated by solving different benchmark problems.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/180462017-01-01T00:00:00ZRAMÍREZ, LuisNOGUEIRA, XesúsOURO, PabloNAVARRINA, FermínKHELLADI, SofianeCOLOMINAS, IgnasiIn this work a higher-order accurate finite volume method for the resolution of the Euler/Navier–Stokes equations using Chimera grid techniques is presented. The formulation is based on the use of Moving Least Squares approximations in order to obtain higher-order accurate reconstruction and connectivity between the overlapped grids. The accuracy and performance of the proposed methodology is demonstrated by solving different benchmark problems.Smoothed Particle Hydrodynamics: A consistent model for interfacial multiphase fluid flow simulations
http://hdl.handle.net/10985/17780
Smoothed Particle Hydrodynamics: A consistent model for interfacial multiphase fluid flow simulations
KRIMI, Abdelkader; REZOUG, Mehdi; KHELLADI, Sofiane; NOGUEIRA, Xesús; DELIGANT, Michael; RAMÍREZ, Luis
In this work, a consistent Smoothed Particle Hydrodynamics (SPH) model to deal with interfacial multiphase fluid flows simulation is proposed. A modification to the Continuum Stress Surface formulation (CSS) [1] to enhance the stability near the fluid interface is developed in the framework of the SPH method. A non-conservative first-order consistency operator is used to compute the divergence of stress surface tensor. This formulation benefits of all the advantages of the one proposed by Adami et al. [2] and, in addition, it can be applied to more than two phases fluid flow simulations. Moreover, the generalized wall boundary conditions [3] are modified in order to be well adapted to multiphase fluid flows with different density and viscosity. In order to allow the application of this technique to wall-bounded multiphase flows, a modification of generalized wall boundary conditions is presented here for using the SPH method. In this work we also present a particle redistribution strategy as an extension of the damping technique presented in [3] to smooth the initial transient phase of gravitational multiphase fluid flow simulations. Several computational tests are investigated to show the accuracy, convergence and applicability of the proposed SPH interfacial multiphase model.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/177802018-01-01T00:00:00ZKRIMI, AbdelkaderREZOUG, MehdiKHELLADI, SofianeNOGUEIRA, XesúsDELIGANT, MichaelRAMÍREZ, LuisIn this work, a consistent Smoothed Particle Hydrodynamics (SPH) model to deal with interfacial multiphase fluid flows simulation is proposed. A modification to the Continuum Stress Surface formulation (CSS) [1] to enhance the stability near the fluid interface is developed in the framework of the SPH method. A non-conservative first-order consistency operator is used to compute the divergence of stress surface tensor. This formulation benefits of all the advantages of the one proposed by Adami et al. [2] and, in addition, it can be applied to more than two phases fluid flow simulations. Moreover, the generalized wall boundary conditions [3] are modified in order to be well adapted to multiphase fluid flows with different density and viscosity. In order to allow the application of this technique to wall-bounded multiphase flows, a modification of generalized wall boundary conditions is presented here for using the SPH method. In this work we also present a particle redistribution strategy as an extension of the damping technique presented in [3] to smooth the initial transient phase of gravitational multiphase fluid flow simulations. Several computational tests are investigated to show the accuracy, convergence and applicability of the proposed SPH interfacial multiphase model.New high-resolution-preserving sliding mesh techniques for higher-order finite volume schemes
http://hdl.handle.net/10985/17818
New high-resolution-preserving sliding mesh techniques for higher-order finite volume schemes
RAMÍREZ, Luis; FOULQUIÉ, Charles; NOGUEIRA, Xesús; KHELLADI, Sofiane; CHASSAING, Jean-Camille; COLOMINAS, Ignasi
This paper presents a new sliding mesh technique for the computation of unsteady viscous flows in the presence of rotating bodies. The compressible Euler and incompressible Navier–Stokes equations are solved using a higher-order (>2) finite volume method on unstructured grids. A sliding mesh approach is employed at the interface between computational grids in relative motion. In order to prevent loss of accuracy, two distinct families of higher-order sliding mesh interfaces are developed. These approaches fit naturally in a high-order finite volume framework. To this end, Moving Least Squares (MLS) approximants are used for the transmission of the information from one grid to another. A particular attention is paid for the study of the accuracy and conservation properties of the numerical scheme for static and rotating grids. The capabilities of the present solver to compute complex unsteady vortical flow motions created by rotating geometries are illustrated on a cross-flow configuration.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/178182015-01-01T00:00:00ZRAMÍREZ, LuisFOULQUIÉ, CharlesNOGUEIRA, XesúsKHELLADI, SofianeCHASSAING, Jean-CamilleCOLOMINAS, IgnasiThis paper presents a new sliding mesh technique for the computation of unsteady viscous flows in the presence of rotating bodies. The compressible Euler and incompressible Navier–Stokes equations are solved using a higher-order (>2) finite volume method on unstructured grids. A sliding mesh approach is employed at the interface between computational grids in relative motion. In order to prevent loss of accuracy, two distinct families of higher-order sliding mesh interfaces are developed. These approaches fit naturally in a high-order finite volume framework. To this end, Moving Least Squares (MLS) approximants are used for the transmission of the information from one grid to another. A particular attention is paid for the study of the accuracy and conservation properties of the numerical scheme for static and rotating grids. The capabilities of the present solver to compute complex unsteady vortical flow motions created by rotating geometries are illustrated on a cross-flow configuration.Numerical assessment of fan blades screen effect on fan/OGV interaction tonal noise
http://hdl.handle.net/10985/19543
Numerical assessment of fan blades screen effect on fan/OGV interaction tonal noise
FOULQUIÉ, Charles; KHELLADI, Sofiane; DELIGANT, Michael; RAMÍREZ, Luis; NOGUEIRA, Xesús; MARDJONO, Jacky
This work deals with sound generation and transmission in a fan stage. The study is done on a subsonic Fan stage and interaction noise between the fan wakes and the Outlet Guide Vanes (OGV) is considered. For this purpose, the Linearized Euler Equations (LEE) are solved with a steady axisymmetric ﬂow. The acoustic sources are modelled by a scattering approach. Numerical simulations are carried out in an unwrapped cylindrical layer using a high-order ﬁnite volume solver. In order to explicitly take into account the moving fan blades into the propagation medium, a high-resolution sliding mesh technique is used. The simulation results, which highlight the screen effect of moving fan blades on fan/OGV interaction tones, are consistent with analytical literature.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/195432020-01-01T00:00:00ZFOULQUIÉ, CharlesKHELLADI, SofianeDELIGANT, MichaelRAMÍREZ, LuisNOGUEIRA, XesúsMARDJONO, JackyThis work deals with sound generation and transmission in a fan stage. The study is done on a subsonic Fan stage and interaction noise between the fan wakes and the Outlet Guide Vanes (OGV) is considered. For this purpose, the Linearized Euler Equations (LEE) are solved with a steady axisymmetric ﬂow. The acoustic sources are modelled by a scattering approach. Numerical simulations are carried out in an unwrapped cylindrical layer using a high-order ﬁnite volume solver. In order to explicitly take into account the moving fan blades into the propagation medium, a high-resolution sliding mesh technique is used. The simulation results, which highlight the screen effect of moving fan blades on fan/OGV interaction tones, are consistent with analytical literature.Multiphase smoothed particle hydrodynamics approach for modeling soil–water interactions
http://hdl.handle.net/10985/17779
Multiphase smoothed particle hydrodynamics approach for modeling soil–water interactions
KRIMI, Abdelkader; KHELLADI, Sofiane; NOGUEIRA, Xesús; DELIGANT, Michael; ATA, Riadh; REZOUG, Mehdi
In this work, a weakly compressible smoothed particle hydrodynamics (WCSPH) multiphase model is developed. The model is able to deal with soil-water interactions coupled in a strong and natural form. A Regularized Bingham Plastic constitutive law including a pressure-dependent Mohr-Coulomb yield criterion (RBPMC-αμ) is proposed to model fluids, soils and their interaction. Since the proposed rheology model is pressure-sensitive, we propose a multiphase diffusive term to reduce the spurious pressure resulting from the weakly compressible flow hypothesis. Several numerical benchmarks are investigated to assess the robustness and accuracy of the proposed multiphase SPH model.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/177792018-01-01T00:00:00ZKRIMI, AbdelkaderKHELLADI, SofianeNOGUEIRA, XesúsDELIGANT, MichaelATA, RiadhREZOUG, MehdiIn this work, a weakly compressible smoothed particle hydrodynamics (WCSPH) multiphase model is developed. The model is able to deal with soil-water interactions coupled in a strong and natural form. A Regularized Bingham Plastic constitutive law including a pressure-dependent Mohr-Coulomb yield criterion (RBPMC-αμ) is proposed to model fluids, soils and their interaction. Since the proposed rheology model is pressure-sensitive, we propose a multiphase diffusive term to reduce the spurious pressure resulting from the weakly compressible flow hypothesis. Several numerical benchmarks are investigated to assess the robustness and accuracy of the proposed multiphase SPH model.A high-order finite volume method with improved isotherms reconstruction for the computation of multiphase flows using the Navier–Stokes–Korteweg equations
http://hdl.handle.net/10985/18007
A high-order finite volume method with improved isotherms reconstruction for the computation of multiphase flows using the Navier–Stokes–Korteweg equations
MARTÍNEZ, Abel; RAMÍREZ, Luis; NOGUEIRA, Xesús; KHELLADI, Sofiane; NAVARRINA, Fermín
In this work we solve the Navier–Stokes–Korteweg (NSK) equations to simulate a two-phase fluid with phase change. We use these equations on a diffuse interface approach, where the properties of the fluid vary continuously across the interface that separates the different phases. The model is able to describe the behavior of both phases with the same set of equations, and it is also able to handle problems with great changes in the topology of the problem. However, high-order derivatives are present in NSK equations, which is a difficulty for the design of a numerical method to solve the problem. Here, we propose the use of a high-order Finite Volume method with Moving Least Squares approximations to handle high-order derivatives and solve the NSK equations. Moreover, a new methodology to obtain accurate equations of state is presented. In this method, we use any accurate equation of state for the pure phases. Under the saturation curve, a B-spline reconstruction fulfilling a given set of thermodynamic criteria is performed. The new EOS can be used for computations using diffuse interface modeling. Several numerical examples to show the accuracy of the new approach are presented.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/180072020-01-01T00:00:00ZMARTÍNEZ, AbelRAMÍREZ, LuisNOGUEIRA, XesúsKHELLADI, SofianeNAVARRINA, FermínIn this work we solve the Navier–Stokes–Korteweg (NSK) equations to simulate a two-phase fluid with phase change. We use these equations on a diffuse interface approach, where the properties of the fluid vary continuously across the interface that separates the different phases. The model is able to describe the behavior of both phases with the same set of equations, and it is also able to handle problems with great changes in the topology of the problem. However, high-order derivatives are present in NSK equations, which is a difficulty for the design of a numerical method to solve the problem. Here, we propose the use of a high-order Finite Volume method with Moving Least Squares approximations to handle high-order derivatives and solve the NSK equations. Moreover, a new methodology to obtain accurate equations of state is presented. In this method, we use any accurate equation of state for the pure phases. Under the saturation curve, a B-spline reconstruction fulfilling a given set of thermodynamic criteria is performed. The new EOS can be used for computations using diffuse interface modeling. Several numerical examples to show the accuracy of the new approach are presented.A very accurate Arbitrary Lagrangian–Eulerian meshless method for Computational Aeroacoustics
http://hdl.handle.net/10985/17782
A very accurate Arbitrary Lagrangian–Eulerian meshless method for Computational Aeroacoustics
RAMÍREZ, Luis; NOGUEIRA, Xesús; KHELLADI, Sofiane; KRIMI, Abdelkader; COLOMINAS, Ignasi
In this work, we propose a new meshless approach based on a Galerkin discretization of a set of conservation equations on an Arbitrary Lagrangian–Eulerian framework. In particular, we solve the Linearized Euler Equations, using Moving Least Squares as weight functions in the Galerkin discretization. Riemann solvers are introduced in the formulation for the discretization of the convective fluxes. Differently from a purely Lagrangian approach, as it is usual in SPH, the present method is able to work in both Eulerian and Lagrangian configurations, which allows using all the advantages of the Lagrangian approaches in the context of Computational Aeroacoustics.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/177822018-01-01T00:00:00ZRAMÍREZ, LuisNOGUEIRA, XesúsKHELLADI, SofianeKRIMI, AbdelkaderCOLOMINAS, IgnasiIn this work, we propose a new meshless approach based on a Galerkin discretization of a set of conservation equations on an Arbitrary Lagrangian–Eulerian framework. In particular, we solve the Linearized Euler Equations, using Moving Least Squares as weight functions in the Galerkin discretization. Riemann solvers are introduced in the formulation for the discretization of the convective fluxes. Differently from a purely Lagrangian approach, as it is usual in SPH, the present method is able to work in both Eulerian and Lagrangian configurations, which allows using all the advantages of the Lagrangian approaches in the context of Computational Aeroacoustics.A high-order density-based finite volume method for the computation of all-speed flows
http://hdl.handle.net/10985/17850
A high-order density-based finite volume method for the computation of all-speed flows
NOGUEIRA, Xesús; RAMÍREZ, Luis; KHELLADI, Sofiane; CHASSAING, Jean-Camille; COLOMINAS, Ignasi
In this paper we present a high-order density-based finite-volume framework for all-speed flows. The formulation is based on high-order variable reconstructions performed using Moving Least Squares approximations. In particular, we show that combining high-order discretization schemes with low-Mach fixes, it is possible to remove the grid dependency problem at low Mach numbers on both structured and unstructured grids. In order to maintain the accuracy and the robustness of the numerical method at transonic conditions, different procedures are proposed, based on the use of a selective limiting.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/178502016-01-01T00:00:00ZNOGUEIRA, XesúsRAMÍREZ, LuisKHELLADI, SofianeCHASSAING, Jean-CamilleCOLOMINAS, IgnasiIn this paper we present a high-order density-based finite-volume framework for all-speed flows. The formulation is based on high-order variable reconstructions performed using Moving Least Squares approximations. In particular, we show that combining high-order discretization schemes with low-Mach fixes, it is possible to remove the grid dependency problem at low Mach numbers on both structured and unstructured grids. In order to maintain the accuracy and the robustness of the numerical method at transonic conditions, different procedures are proposed, based on the use of a selective limiting.