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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 06 Aug 2024 08:34:35 GMT2024-08-06T08:34:35ZExternal Laminar Boundary Layer Simulations Using a High-Fidelity Wall-Modeling Approach
http://hdl.handle.net/10985/23662
External Laminar Boundary Layer Simulations Using a High-Fidelity Wall-Modeling Approach
VIANA DAURICIO, Eron Tiago; JUNQUEIRA JUNIOR, Carlos; FEROLLA DE ABREU, Diego; AZEVEDO, João Luiz F.
Wall-Modeled Large Eddy Simulation (WMLES) is a well-stablished technique for obtaining high-fidelity solutions of turbulent, high Reynolds number flows, with reasonably acceptable computational costs. However, for external flows, the very thin laminar boundary layer developing near the body leading edge imposes quite restrictive mesh resolution requirements, leading to prohibitively high computational costs for practical Reynolds numbers. We propose a wall-modeling approach for the laminar portion of the boundary layer in order to alleviate these costs by reducing the aforementioned mesh resolution requirements. The wall model is based on local self-similar solutions of the boundary layer, and is implemented in the same context of wall-stress models in the WMLES approach. An assessment of the model is done in terms of both pressure and skin friction coefficient distributions along the surface, for an incompressible, fully laminar flow around a NACA 0012 airfoil geometry, with a chord Reynolds number of Re_c = 4500. The results obtained in the simulations using the proposed model are in good agreement with the reference solution, demonstrating the feasibility of the model for external laminar flows.
Tue, 01 Nov 2022 00:00:00 GMThttp://hdl.handle.net/10985/236622022-11-01T00:00:00ZVIANA DAURICIO, Eron TiagoJUNQUEIRA JUNIOR, CarlosFEROLLA DE ABREU, DiegoAZEVEDO, João Luiz F.Wall-Modeled Large Eddy Simulation (WMLES) is a well-stablished technique for obtaining high-fidelity solutions of turbulent, high Reynolds number flows, with reasonably acceptable computational costs. However, for external flows, the very thin laminar boundary layer developing near the body leading edge imposes quite restrictive mesh resolution requirements, leading to prohibitively high computational costs for practical Reynolds numbers. We propose a wall-modeling approach for the laminar portion of the boundary layer in order to alleviate these costs by reducing the aforementioned mesh resolution requirements. The wall model is based on local self-similar solutions of the boundary layer, and is implemented in the same context of wall-stress models in the WMLES approach. An assessment of the model is done in terms of both pressure and skin friction coefficient distributions along the surface, for an incompressible, fully laminar flow around a NACA 0012 airfoil geometry, with a chord Reynolds number of Re_c = 4500. The results obtained in the simulations using the proposed model are in good agreement with the reference solution, demonstrating the feasibility of the model for external laminar flows.Large-eddy simulations of turbulent compressible supersonic jet flows using discontinuous Galerkin methods
http://hdl.handle.net/10985/23681
Large-eddy simulations of turbulent compressible supersonic jet flows using discontinuous Galerkin methods
F. ABREU, Diego; JUNQUEIRA JUNIOR, Carlos; DAURICIO, Eron; F. AZEVEDO, João Luiz
In this work, a discontinuous Galerkin scheme is employed to perform the simulations of supersonic jet flows. A total of four simulations are performed with different meshes and order of accuracy. The number of degrees of freedom from the simulations varies from 50 × 10^6 to 400 × 10^6. The results indicate that by increasing the resolution of simulation, in general, the results got closer to experimental data. The jet lipline is the only region in which this behavior is not observed. It investigated a procedure of using lower-order simulations to initialize high-order simulations and consequently reduce the total time of the simulation using high-order schemes. This strategy is successful and allows to perform high-order simulations with only 5% more computational effort than a complete second-order simulation.
Wed, 01 Jun 2022 00:00:00 GMThttp://hdl.handle.net/10985/236812022-06-01T00:00:00ZF. ABREU, DiegoJUNQUEIRA JUNIOR, CarlosDAURICIO, EronF. AZEVEDO, João LuizIn this work, a discontinuous Galerkin scheme is employed to perform the simulations of supersonic jet flows. A total of four simulations are performed with different meshes and order of accuracy. The number of degrees of freedom from the simulations varies from 50 × 10^6 to 400 × 10^6. The results indicate that by increasing the resolution of simulation, in general, the results got closer to experimental data. The jet lipline is the only region in which this behavior is not observed. It investigated a procedure of using lower-order simulations to initialize high-order simulations and consequently reduce the total time of the simulation using high-order schemes. This strategy is successful and allows to perform high-order simulations with only 5% more computational effort than a complete second-order simulation.Numerical investigation of sheet cavitation over a 3-D venturi configuration
http://hdl.handle.net/10985/23682
Numerical investigation of sheet cavitation over a 3-D venturi configuration
GOUIN, Camille; JUNQUEIRA JUNIOR, Carlos; GONCALVES, Eric; ROBINET, Jean-Christophe
Sheet cavitation appears in many hydraulic applications and can lead to technical issues. Numerical simulation is a pertinent way to study the phenomenon. A numerical tool based on 1-fluid compressible RANS equations with a cavitation model is used to compute a flow within a 3-D venturi geometry with a 4° divergent angle. In the present work, a detailed study of this cavitating flow, which presents a quasi-stable vapour pocket, is carried out using tools such as Power Spectral Densities or Spectral Proper Orthogonal Decompositions. An oblique oscillation of the cavity is then identified and discussed.
Sat, 01 May 2021 00:00:00 GMThttp://hdl.handle.net/10985/236822021-05-01T00:00:00ZGOUIN, CamilleJUNQUEIRA JUNIOR, CarlosGONCALVES, EricROBINET, Jean-ChristopheSheet cavitation appears in many hydraulic applications and can lead to technical issues. Numerical simulation is a pertinent way to study the phenomenon. A numerical tool based on 1-fluid compressible RANS equations with a cavitation model is used to compute a flow within a 3-D venturi geometry with a 4° divergent angle. In the present work, a detailed study of this cavitating flow, which presents a quasi-stable vapour pocket, is carried out using tools such as Power Spectral Densities or Spectral Proper Orthogonal Decompositions. An oblique oscillation of the cavity is then identified and discussed.