High-Order Schemes for Navier-Stokes Equations: Algorithm and Implementation Into FDL3DI

Gaitonde, Datta V.; Visbal, Miguel R.

doi:10.21236/ada364301

Cited by 494 publications

(205 citation statements)

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“…A four-stage optimized explicit Runge-Kutta scheme [24] is used to advance the time solution. A seven-point Padé filter with the free parameter α f = 0.40 [25] is performed every two time steps at the computational coordinates to eliminate the parasite waves. The radiation and outflow non-reflecting boundary conditions [26,27] are used at the inflow, far-field, and outflow boundary, respectively.…”

Section: Methodsmentioning

confidence: 99%

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Ran

Wan

et al. 2017

Acta Mech. Sin.

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Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier-Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear, and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at downstream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.

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Section: Methodsmentioning

confidence: 99%

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Ran

Wan

et al. 2017

Acta Mech. Sin.

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“…Após cada passo temporalé feita uma filtragem numérica para evitar o surgimento de ondas de altas frequência sem sentido físico causadas pelo ruído numérico, como mostrado por [4]. Essa filtragem envolve resolver, para o domínio todo, um sistema linear da forma…”

Section: Esquemas Numéricosunclassified

Aeroacústica de emparelhamento de vórtices em esteiras assimétricas

Mathias

Gennaro

Medeiros

2015

Proceeding Series of the Brazilian Society of Computational and Applied Mathematics

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Resumo: O objetivo deste estudoé analisar a aeroacústica de esteiras assimétricas. Tal escoamento pode ser encontrados a jusante de perfis aerodinâmicos que geram sustentação, dispositivos hipersustentadores de aeronaves ou de tubos próximos a paredes, por exemplo. A evolução do escoamentoé calculada por simulação numérica direta, na qual são induzidas perturbações controladas, podendo-se obter o comportamento aeroacústico para diferentes frequências. São formados vórtices assimétricos que se emparelham. Tanto a formação quanto o emparelhamento geram som. Devidoà assimetria, este som se propaga de maneira distinta em diferentes direções. Estudando-se os fatores que influenciam nesta distribuição pode-se entender melhor a aeroacústica de corpos de formas mais complexas. Futuramente tal conhecimento pode ser aplicado na concepção de aeronaves mais silenciosas, cumprindo requisitos ambientais mais rígidos.Palavras-chave: Aeroacústica, DNS, Escoamento Cisalhante, Esteira Assimétrica IntroduçãoDurante procedimentos de pouso ou decolagem uma aeronave produz um alto nível de ruído. Tem havido um crescimento nas exigências ambientais nas proximidades de aeroportos. Com o avanço na tecnologia de motores mais silenciosos, os dispositivos hipersustentadores passaram a ter uma posição de destaque entre as fontes sonoras, em especial os slats durante o pouso.Escoamentos viscosos ao redor de corpos rombudos geram uma esteira; onde, em uma certa faixa de número de Reynolds, passa a ocorrer um desprendimento de vórtices devidoà instabilidade. Em corpos que geram sustentação,à esteiraé somada uma componente assimétrica. Essé e o caso de slats, flaps e outros dispositivos aerodinâmicos.Em uma esteira simétrica o sistema de vórtices gera relativamente pouco som. Nestes casos a geração sonora está associadaà força oscilatória sobre o corpo. Isto se deve ao fato de que o arranjo de vórtices em uma esteira simétricaé muito estável não ocorrendo grande deformação nos vórtices, o queé um mecanismo importante de geração de som.No caso assimétrico, esses vórtices possuem intensidades diferentes, e a instabilidade que se verifica no caso simétricoé perdida. No arranjo assimétrico ocorrem grandes deformações neste

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“…However, it is important to ensure that filtering only removes the high frequency information and does not affect the turbulent structures globally. This is accomplished through the use of a sixth order accurate implicit filtering procedure described in [12]. The constant prescribing the quality of the filtering, a, is set as 0.25 here.…”

Section: Numerical Frameworkmentioning

confidence: 99%

LES of Gas Exchange in IC Engines

Mittal

Kang

Doran

et al. 2013

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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and available online here Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 69, n°1, et téléchargeable ici D o s s i e rDOSSIER Edited by/Sous la direction de : C. Angelberger IFP Energies nouvelles International Conference / Les Rencontres Scientifiques d'IFP Energies nouvelles LES4ICE 2012 -Large Eddy Simulation for Internal Combustion Engine FlowsLES4ICE 2012 -La simulation aux grandes échelles pour les écoulements dans les moteurs à combustion interne Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 69 (2014) Abstract -LES of Gas Exchange in IC Engines -As engine technologies become increasingly complex and engines are driven to new operating points, understanding transient phenomena is important to ensure reliable engine operation. Unlike Reynolds Averaged Navier-Stokes (RANS) studies that only provide cycle-averaged information, Large Eddy Simulation (LES) studies are capable of simulating cycle-to-cycle dynamics. In this work, a finite difference based structured methodology for LES of IC engines is presented. This structured approach allows for an efficient mesh generation process and provides potential for higher order numerical accuracy. An efficient parallel scalable block decomposition is done to overcome the challenges associated with the low ratio of fluid elements to overall mesh elements. The motion of the valves and piston is handled using a dynamic cell blanking approach and the Arbitrary Lagrangian Eulerian (ALE) method, respectively. Modified three-dimensional Navier-Stokes Characteristic Boundary Conditions (NSCBC) Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 69 (2014), No. 1, pp. 29-40 Copyright Ó 2013, IFP Energies nouvelles DOI: 10.2516 are used in the simulation to prescribe conditions in the manifolds. The accuracy of the simulation framework is validated using various canonical configurations. Flow bench simulations of an axisymmetric configuration and an actual engine geometry are done with the LES methodology. Simulations of the gas exchange in an engine under motored conditions are also performed. Overall, good agreement is obtained with experiments for all the cases. Therefore, this framework can be used for LES of engine simulations. In the future, reactive LES simulations will be performed using this framework.

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High-Order Schemes for Navier-Stokes Equations: Algorithm and Implementation Into FDL3DI

Cited by 494 publications

References 10 publications

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Instability waves and low-frequency noise radiation in the subsonic chevron jet

Aeroacústica de emparelhamento de vórtices em esteiras assimétricas

LES of Gas Exchange in IC Engines

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