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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 25 Jan 2020 23:03:20 GMT2020-01-25T23:03:20ZA 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.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.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.