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Thursday, July 30, 2020 | History

3 edition of Towards understanding turbulent scalar mixing found in the catalog.

Towards understanding turbulent scalar mixing

Towards understanding turbulent scalar mixing

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  • 25 Currently reading

Published by National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, National Technical Information Service, distributor] in [Washington, DC], [Springfield, Va.? .
Written in English

    Subjects:
  • Turbulence.

  • Edition Notes

    StatementSharath S. Girimaji.
    SeriesNASA contractor report -- 4446., NASA contractor report -- NASA CR-4446.
    ContributionsUnited States. National Aeronautics and Space Administration. Scientific and Technical Information Program.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17786327M

      etc. Understanding the statistical behavior of scalar uctuations and their gradients is important both from the application as well as the fundamental points of view. Most of the industrial processes (for instance heat exchange, mixing, combustion) involve the transport of scalar by a turbulent ow. Similarly, understanding of micro-mixing, and /turbulence-mixing-and-flow-control-group/IP_PRFpdf.   EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET A Thesis Presented to the Graduate School of Clemson University In Partial Fulflllment of the Requirements for the Degree Master of Science Mechanical Engineering by Matthew J. Dinger May Accepted by: Dr. Chenning Tong, Committee Chair Dr. Richard Miller Dr ?article=&context=all_theses.

      A study of turbulence and scalar mixing in a wall-jet using direct numerical simulation Daniel Ahlman Dept. of Mechanics, Royal Institute of Technology SE 44 Stockholm, Sweden Abstract Direct numerical simulation is used to study the dynamics and mixing in a turbulent plane wall-jet. The investigation is undertaken in order to extend Improvements in Turbulent Scalar Mixing Modeling for Trailing Edge Slot Film Cooling Geometries: A Combined Experimental and Computational Approach.. United States: N.

      Passive scalar dispersion and mixing in a turbulent jet. J. Fluid Mech. –38 Van Atta CW. Local isotropy of the smallest scales of turbulent scalar and   3 Passive Scalar Transport in Turbulence: - Ten Chapters in Turbulence Edited by Peter A. Davidson, Yukio Kaneda and katepalli R. Sreenivasan Frontmatter More information. x Preface understanding of turbulent mixing and dispersion, allowing us to probe


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Towards understanding turbulent scalar mixing Download PDF EPUB FB2

In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity :// /_Towards_understanding_turbulent_scalar_mixing.

In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity field. The chief motivation for this approach stems from the strong resemblance of the scalar probability density function (PDF) obtained from the scalar field evolving In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity field.

The chief motivation for this approach stems from the strong resemblance of the scalar probability density function (PDF) obtained from the scalar field evolving G. Get this from a library. Towards understanding turbulent scalar mixing. [Sharath S Girimaji; United States.

National Aeronautics and Space Administration. Scientific and Technical Information Program.]   In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity field.

The chief motivation for this approach stems from the strong resemblance of the scalar probability density function (PDF) obtained from the scalar field evolving from the heat conduction equation that arises in a The Mapping closure concept was first introduced by Chen, Chen, and Kraichnan () to model turbulent scalar mixing.

Since then it has been modified and extended to multiscalar mixing. In this paper, the time-evolving reference-field version of the mapping closure   Towards Understanding the Mixing Characteristics of Turbulent Buoyant Flows Thesis by Phares L.

Carroll In Partial Ful llment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California (Defended Ap )   Towards understanding turbulent mixing Sharath S. Girimaji A.

& M. Inc., Hampton, Virginia scalar Abstract In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then ac-counting for the effects of the velocity field. The chief motivation for Within this shear layer, turbulent mixing of scalar quantities like salt and heat takes place.

The Reynolds number of turbulence is expected to attain very high values (Re lambda=). As a result of very high Reynolds number, Peclet number for temperature and salinity fields are also very high in the mixing Most turbulent heat flux models, which are based on isotropic diffusion with a fixed turbulent Prandtl number (Pr t), fail to accurately predict heat transfer in film cooling flows.

In the present work, machine learning models are trained to predict a non-uniform Pr t field using various datasets as training :// Abstract. This work proposes a new simulation methodology in which variable density turbulent flows can be studied in the context of a mixing layer with or without the presence   A methodology for modeling passive scalar mixing in homogeneous turbulence using a new mapping closure approach is developed.

The physical scalar field φ(y,t) (y‐space coordinate, t time) is mapped using a mapping function, X(t), onto a reference scalar field θ(y,t), whose evolution is are two main differences between the present approach and that of Chen et :// Abstract. The streamwise evolution of the highest concentration C max of a passive scalar in a turbulent round jet is measured in the range (0 ≤ x/d ≤ 20).

The Schmidt number was Sc≅ 4 and the jet Reynolds number Re d ≅ Beyond the near field of the jet nozzle (x/d ≤ 4) the C max decreases. This finding needs to be taken into account in scalar probability density function   On the modeling of scalar diffusion in isotropic turbulence Physics of Fluids A: Fluid Dynamics 4, ( “ Direct numerical simulations of the turbulent mixing of a passive scalar,” Phys.

Flu “Towards understanding turbulent scalar mixing,” NASA Contract. Rep. This work proposes a new simulation methodology in which variable density turbulent flows can be studied in the context of a mixing layer with or without the presence of gravity. This methodology is developed to probe the nature of non-buoyantly-driven or buoyantly-driven mixing inside a mixing layer.

Numerical forcing methods are incorporated into the velocity and scalar fields, extending the C/abstract. Turbulent mixing, defined as the dissipation of scalar variance, is “intermittent” 7,9,10 —it occurs in spatio-temporal bursts qualitatively similar to the energy dissipation by the Towards understanding the mixing characteristics of turbulent buoyant flows despite the differences noted between fully buoyant and non-buoyant turbulent fields, the scalar field, in all cases, is unchanged by these.

The mixing dynamics in the scalar field are found to be insensitive to the source of turbulent kinetic energy production (non In the present study we investigate three-stream scalar mixing in a turbulent coaxial jet. In this flow the center jet and the annulus, consisting of acetone-doped air and ethylene respectively, are mixed with the co-flow air.

A unique aspect of this study compared to previous studies of three-scalar mixing is that two of the scalars (the center jet and air) are separated from the third Mixing in turbulent flows is greatly enhanced, which enables the operation of highly efficient combustion engines and sophisticated chemical reactors in the first place.

Therefore, a better understanding of the behavior and underlying mechanisms of turbulent flows is of great practical importance which is not limited to combustion :// The most fundamental problem is scalar dispersion from a concentrated source in the simplest turbulent flow: homogeneous, isotropic turbulence.

Though basic in principle, its details are nevertheless complex. The difficulties increase when consi-dering scalar mixing from a concentrated source in homogeneous, but anisotropic, turbulent shear ?doi=&rep=rep1&type=pdf.

In turbulent scalar mixing, starting from random initial conditions, the root-mean-square advection term rapidly drops as the flow and the scalar field ://  A passive scalar is mixed by the flow, but it has no effect on the flow. It can represent, for example, small temperature fluctuations or a pollutant carried by the flow.

Knowledge of passive scalar mixing is also a first step towards the understanding of reactive flows, where the mixing of species plays an im-portant ://  transport of the turbulent stresses and fluxes. A simple algebraic relation is used to close the problem. Based on the mixing length theory, which is the length over which there is high interaction of vortices in a turbulent flow field, dimensional analysis is used to show that: t tmm dU lu l l 7