A New Paradigm for Turbulence Control for Drag Reduction

reportActive / Technical Report | Accession Number: AD1030879 | Open PDF

Abstract:

Direct numerical simulations DNS of span wise-rotating turbulent channel flow as well as the neutral and unstable turbulent Ekman layer were conducted. These DNS results were used to evaluate various turbulence and heat transfer models for the Reynolds stresses, turbulent heat fluxes and higher-order moments of velocity and temperature. Explicit Algebraic Reynolds Stress Models EARSM obtained the Reynolds stress distributions in best agreement with DNS data for rotational flows and turbulent heat flux distributions obtained from two explicit algebraic heat flux models consistently displayed increasing disagreement with DNS data with increasing rotation rate. DNS results were also used to determine the proper computational box size for a minimal flow unit MFU at Rob0.5. For the neutrally stratified Ekman layer, the higher-order moments of velocity were examined and the accuracy of a kurtosis model was assessed. For the unstable Ekman layer, the analysis of higher-order moments was extended to temperature-velocity correlations.

Author(s):
Hussein, Mahmoud
Author Organization(s):
Regents of the University of Colorado Boulder United States
Descriptive Note:
Technical Report,30 Sep 2015,29 Sep 2016
Pagination:
0020

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release
Distribution Statement:
Approved For Public Release;

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
AFRL-AFOSR-VA-TR-2017-0059
Monitor Series:
AFRL-AFOSR-VA-TR-2017-0059
 Subject Terms
Joint Capability Areas:
JCA_3.2_Engagement; JCA_3_Force Application; JCA_3.2.1_Kinetic Means; JCA_5_Command and Control; JCA_5.3_Planning; JCA_1_Force Support; JCA_1.2_Force Preparation; JCA_5.5.2_Task; JCA_5.5_Direct; JCA_8_Building Partnerships
Modernization Areas:
Quantum Science and Computing
Communities of Interest:
Energy and Power Technologies
Descriptor(s):
boundary layer, computational fluid dynamics, channel flow, heat transfer, energy transfer, hypervelocity flow, kinetic energy, reynolds number, drag, energy bands, simulations, temperature gradients, turbomachinery, turbulent flow, heat flux, mathematical models
Field(s)/Group(s):
Fluid Mechanics
Keyword(s):
dns(Direct numerical simulations), spanwise rotating turbulent channel, Reynolds stresses, earsm(Explicit Algebraic Reynolds Stress Models)
Report Date:
2017 Feb 27
Creation Date:
2017 Jul 11