Publication detail

On stochastic inlet boundary condition for unsteady simulations

NIEDOBA, P. JÍCHA, M. ČERMÁK, L.

Original Title

On stochastic inlet boundary condition for unsteady simulations

English Title

On stochastic inlet boundary condition for unsteady simulations

Type

conference paper

Language

en

Original Abstract

The paper deals with the stochastic generation of synthesized turbulence, which may be used for a generating of an inlet boundary condition for unsteady simulations, e.g. Direct Numerical Simulation (DNS) or Large Eddy Simulation (LES). Assumptions for the generated turbulence are isotropy and homogeneity. The described method produces a stochastic turbulent velocity field using the synthesis of a finite sum of random Fourier modes. The calculation of individual Fourier modes is based on known energy spectrum of turbulent flow, and some turbulent quantities, e.g. turbulent kinetic energy and turbulent dissipation rate. A division of wave number range of the energy spectrum determines directly the number of Fourier modes, and has a direct impact on accuracy and speed of this calculation. Therefore, this work will examine the influence of the number of Fourier modes on a conservation of the first and second statistical moments of turbulent velocity components, which are prespecified. It is important to ensure a sufficient size of a computational domain, and a sufficient number of cells for meaningful comparative results. Dimensionless parameters characterizing the resolution and size of the computational domain according to a turbulent length scale will be introduced for this purpose. Subsequently, the sufficient values of this parameters will be shown for individual numbers of Fourier modes.

English abstract

The paper deals with the stochastic generation of synthesized turbulence, which may be used for a generating of an inlet boundary condition for unsteady simulations, e.g. Direct Numerical Simulation (DNS) or Large Eddy Simulation (LES). Assumptions for the generated turbulence are isotropy and homogeneity. The described method produces a stochastic turbulent velocity field using the synthesis of a finite sum of random Fourier modes. The calculation of individual Fourier modes is based on known energy spectrum of turbulent flow, and some turbulent quantities, e.g. turbulent kinetic energy and turbulent dissipation rate. A division of wave number range of the energy spectrum determines directly the number of Fourier modes, and has a direct impact on accuracy and speed of this calculation. Therefore, this work will examine the influence of the number of Fourier modes on a conservation of the first and second statistical moments of turbulent velocity components, which are prespecified. It is important to ensure a sufficient size of a computational domain, and a sufficient number of cells for meaningful comparative results. Dimensionless parameters characterizing the resolution and size of the computational domain according to a turbulent length scale will be introduced for this purpose. Subsequently, the sufficient values of this parameters will be shown for individual numbers of Fourier modes.

Keywords

computaional fluid dynamics, inlet boundary condition, synthesized turbulence, Fourier mode

RIV year

2013

Released

19.11.2013

Publisher

EDP Sciences

Location

Kutná Hora

ISBN

978-80-260-5375-0

Book

EPJ Web of Conferences

Pages from

495

Pages to

498

Pages count

4

URL

Full text in the Digital Library

BibTex


@inproceedings{BUT104111,
  author="Pavel {Niedoba} and Miroslav {Jícha} and Libor {Čermák}",
  title="On stochastic inlet boundary condition for unsteady simulations",
  annote="The paper deals with the stochastic generation of synthesized turbulence, which may be used for
a generating of an inlet boundary condition for unsteady simulations, e.g. Direct Numerical Simulation (DNS)
or Large Eddy Simulation (LES). Assumptions for the generated turbulence are isotropy and homogeneity. The
described method produces a stochastic turbulent velocity field using the synthesis of a finite sum of random
Fourier modes. The calculation of individual Fourier modes is based on known energy spectrum of turbulent
flow, and some turbulent quantities, e.g. turbulent kinetic energy and turbulent dissipation rate. A division of wave
number range of the energy spectrum determines directly the number of Fourier modes, and has a direct impact on
accuracy and speed of this calculation. Therefore, this work will examine the influence of the number of Fourier
modes on a conservation of the first and second statistical moments of turbulent velocity components, which are
prespecified. It is important to ensure a sufficient size of a computational domain, and a sufficient number of
cells for meaningful comparative results. Dimensionless parameters characterizing the resolution and size of the
computational domain according to a turbulent length scale will be introduced for this purpose. Subsequently,
the sufficient values of this parameters will be shown for individual numbers of Fourier modes.",
  address="EDP Sciences",
  booktitle="EPJ Web of Conferences",
  chapter="104111",
  doi="10.1051/epjconf/20146702082",
  howpublished="online",
  institution="EDP Sciences",
  number="1",
  year="2013",
  month="november",
  pages="495--498",
  publisher="EDP Sciences",
  type="conference paper"
}