Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer

A.W. Vreman

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    86 Downloads (Pure)

    Abstract

    The Large-Eddy Simulation technique of compressible flows and the effect of compressibility on mixing layers are the main subjects of this thesis. Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES) of the temporal compressible mixing layer at various Mach and Reynolds numbers have been conducted to investigate these subjects. With respect to the LES technique, Large-Eddy Simulations have been performed at convective Mach numbers 0.2, 0.6 and 1.2 and the results have been compared with filtered DNS-data. It appeared that the dynamic subgrid-models lead to relatively accurate results compared to the other models tested. The dynamic approach turned out to yield acceptable results too in LES of a mixing layer that currently cannot be simulated using DNS. Care has to be taken to ensure that the numerical errors in LES are sufficiently small. It was found that these errors are usually sufficiently small if the filter width equals twice the grid-spacing. In addition to modelling the turbulent stress tensor, compressible LES formally requires the modelling of the subgrid-terms in the energy equation, which do not occur in incompressible LES. However, the compressible Large- Eddy Simulations demonstrated that the turbulent stress tensor is the dominant subgrid-term, even at convective Mach number 1.2. This important subgrid-term was also investigated from a theoretical point of view and realizability conditions for this tensor were derived. Regarding compressibility effects in the mixing layer, shock-waves were found in the three-dimensional DNS at convective Mach number 1.2. Furthermore, we have investigated the cause of the mixing layer growth rate reduction with increasing compressibility, using four DNS-databases covering the range of convective Mach numbers from 0.2 to 1.2. It was found that the growth rate reduction cannot be explained by the dilatational terms, but rather by the reduced pressure fluctuations, leading to reduced pressure strain and turbulent production terms.
    Original languageEnglish
    Awarding Institution
    • University of Twente
    Supervisors/Advisors
    • Zandbergen, P.J., Supervisor
    • Geurts, Bernardus J., Supervisor
    Award date14 Dec 1995
    Place of PublicationEnschede
    Publisher
    Print ISBNs90-900884-9
    Publication statusPublished - 14 Dec 1995

    Fingerprint

    turbulent mixing
    large eddy simulation
    Mach number
    stress tensors
    simulation
    compressibility effects
    compressible flow
    theses
    data simulation
    dynamic models
    compressibility
    shock waves
    Reynolds number
    coverings
    spacing
    tensors
    filters
    causes

    Keywords

    • IR-85256
    • METIS-140282

    Cite this

    Vreman, A. W. (1995). Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer. Enschede: University of Twente.
    Vreman, A.W.. / Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer. Enschede : University of Twente, 1995. 152 p.
    @phdthesis{7567a65da1aa49398339ac31d6423a1a,
    title = "Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer",
    abstract = "The Large-Eddy Simulation technique of compressible flows and the effect of compressibility on mixing layers are the main subjects of this thesis. Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES) of the temporal compressible mixing layer at various Mach and Reynolds numbers have been conducted to investigate these subjects. With respect to the LES technique, Large-Eddy Simulations have been performed at convective Mach numbers 0.2, 0.6 and 1.2 and the results have been compared with filtered DNS-data. It appeared that the dynamic subgrid-models lead to relatively accurate results compared to the other models tested. The dynamic approach turned out to yield acceptable results too in LES of a mixing layer that currently cannot be simulated using DNS. Care has to be taken to ensure that the numerical errors in LES are sufficiently small. It was found that these errors are usually sufficiently small if the filter width equals twice the grid-spacing. In addition to modelling the turbulent stress tensor, compressible LES formally requires the modelling of the subgrid-terms in the energy equation, which do not occur in incompressible LES. However, the compressible Large- Eddy Simulations demonstrated that the turbulent stress tensor is the dominant subgrid-term, even at convective Mach number 1.2. This important subgrid-term was also investigated from a theoretical point of view and realizability conditions for this tensor were derived. Regarding compressibility effects in the mixing layer, shock-waves were found in the three-dimensional DNS at convective Mach number 1.2. Furthermore, we have investigated the cause of the mixing layer growth rate reduction with increasing compressibility, using four DNS-databases covering the range of convective Mach numbers from 0.2 to 1.2. It was found that the growth rate reduction cannot be explained by the dilatational terms, but rather by the reduced pressure fluctuations, leading to reduced pressure strain and turbulent production terms.",
    keywords = "IR-85256, METIS-140282",
    author = "A.W. Vreman",
    year = "1995",
    month = "12",
    day = "14",
    language = "English",
    isbn = "90-900884-9",
    publisher = "University of Twente",
    address = "Netherlands",
    school = "University of Twente",

    }

    Vreman, AW 1995, 'Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer', University of Twente, Enschede.

    Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer. / Vreman, A.W.

    Enschede : University of Twente, 1995. 152 p.

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    TY - THES

    T1 - Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer

    AU - Vreman, A.W.

    PY - 1995/12/14

    Y1 - 1995/12/14

    N2 - The Large-Eddy Simulation technique of compressible flows and the effect of compressibility on mixing layers are the main subjects of this thesis. Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES) of the temporal compressible mixing layer at various Mach and Reynolds numbers have been conducted to investigate these subjects. With respect to the LES technique, Large-Eddy Simulations have been performed at convective Mach numbers 0.2, 0.6 and 1.2 and the results have been compared with filtered DNS-data. It appeared that the dynamic subgrid-models lead to relatively accurate results compared to the other models tested. The dynamic approach turned out to yield acceptable results too in LES of a mixing layer that currently cannot be simulated using DNS. Care has to be taken to ensure that the numerical errors in LES are sufficiently small. It was found that these errors are usually sufficiently small if the filter width equals twice the grid-spacing. In addition to modelling the turbulent stress tensor, compressible LES formally requires the modelling of the subgrid-terms in the energy equation, which do not occur in incompressible LES. However, the compressible Large- Eddy Simulations demonstrated that the turbulent stress tensor is the dominant subgrid-term, even at convective Mach number 1.2. This important subgrid-term was also investigated from a theoretical point of view and realizability conditions for this tensor were derived. Regarding compressibility effects in the mixing layer, shock-waves were found in the three-dimensional DNS at convective Mach number 1.2. Furthermore, we have investigated the cause of the mixing layer growth rate reduction with increasing compressibility, using four DNS-databases covering the range of convective Mach numbers from 0.2 to 1.2. It was found that the growth rate reduction cannot be explained by the dilatational terms, but rather by the reduced pressure fluctuations, leading to reduced pressure strain and turbulent production terms.

    AB - The Large-Eddy Simulation technique of compressible flows and the effect of compressibility on mixing layers are the main subjects of this thesis. Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES) of the temporal compressible mixing layer at various Mach and Reynolds numbers have been conducted to investigate these subjects. With respect to the LES technique, Large-Eddy Simulations have been performed at convective Mach numbers 0.2, 0.6 and 1.2 and the results have been compared with filtered DNS-data. It appeared that the dynamic subgrid-models lead to relatively accurate results compared to the other models tested. The dynamic approach turned out to yield acceptable results too in LES of a mixing layer that currently cannot be simulated using DNS. Care has to be taken to ensure that the numerical errors in LES are sufficiently small. It was found that these errors are usually sufficiently small if the filter width equals twice the grid-spacing. In addition to modelling the turbulent stress tensor, compressible LES formally requires the modelling of the subgrid-terms in the energy equation, which do not occur in incompressible LES. However, the compressible Large- Eddy Simulations demonstrated that the turbulent stress tensor is the dominant subgrid-term, even at convective Mach number 1.2. This important subgrid-term was also investigated from a theoretical point of view and realizability conditions for this tensor were derived. Regarding compressibility effects in the mixing layer, shock-waves were found in the three-dimensional DNS at convective Mach number 1.2. Furthermore, we have investigated the cause of the mixing layer growth rate reduction with increasing compressibility, using four DNS-databases covering the range of convective Mach numbers from 0.2 to 1.2. It was found that the growth rate reduction cannot be explained by the dilatational terms, but rather by the reduced pressure fluctuations, leading to reduced pressure strain and turbulent production terms.

    KW - IR-85256

    KW - METIS-140282

    M3 - PhD Thesis - Research UT, graduation UT

    SN - 90-900884-9

    PB - University of Twente

    CY - Enschede

    ER -

    Vreman AW. Direct and Large-Eddy Simulation of the Compressible Turbulent Mixing Layer. Enschede: University of Twente, 1995. 152 p.