GGrantIndex
← Search

THIS PROPOSAL TARGETS THE NRA ROA-2018 WITHIN THE TRANSFORMATIONAL TOOLS AND TECHNOLOGIES (TTT) PROJECT SUBTOPIC 2.1.2 ACCURATE AND EFFICIENT MODELS FOR SCALE RESOLVING SIMULATIONS. DESPITE ITS PROVEN PREDICTIVE CAPABILITY LARGE-EDDY SIMULATION (LES) HAS BEEN DEPLOYED RARELY FOR PRACTICAL EXTERNAL AERODYNAMICS APPLICATIONS DUE TO THE PROHIBITIVE COST INCURRED BY THE NECESSITY OF RESOLVING THE SMALL BUT ENERGETIC MOTIONS IN THE NEAR-WALL REGION OF HIGH REYNOLDS NUMBER TURBULENT FLOWS. NOVEL WALL-MODELING TECHNIQUES THAT HAVE EMERGED IN THE LAST DECADE HAVE THE POTENTIAL OF OVERCOMING THIS BARRIER BY NOT RESOLVING THE TINY NEAR-WALL EDDIES DIRECTLY BUT MODELING THEIR EFFECTS ON THE OUTER-LAYER FLOW. HOWEVER WALL MODELS HAVE NOT BEEN VALIDATED SUFFICIENTLY IN FLOWS EXHIBITING STRONG NONEQUILIBRIUM EFFECTS COMMONLY ENCOUNTERED IN AVIATION APPLICATIONS. IN ADDITION THE METHOD HAS BEEN USED WITH LITTLE ATTENTION ON HOW TO INTERPRET THE SOLUTION OBTAINED FROM SIGNIFICANTLY UNDERRESOLVED SIMULATIONS. THE PROPOSED RESEARCH WILL FOCUS ON EXTENDING THE APPLICABILITY OF WALL-MODELED LARGE-EDDY SIMULATION (WMLES) METHODOLOGIES TO COMPLEX NONEQUILIBRIUM FLOWS. WE PROPOSE TO DO TWO MAJOR TASKS TO ACHIEVE THIS GOAL. FIRST THE PREDICTIVE CAPABILITY OF THE WIDELY USED WALL MODELS WILL BE ASSESSED THOROUGHLY IN FLOWS EXHIBITING STRONG NONEQUILIBRIUM CHARACTERISTICS. THESE INCLUDE FLOW SEPARATION DUE TO MILD ADVERSE PRESSURE GRADIENT BOUNDARY LAYER WITH MEAN THREE DIMENSIONALITY AND CONVECTIVE HEAT TRANSFER UNDER PRESSURE GRADIENT. THIS WILL HELP US TO IDENTIFY THE RANGE OF APPLICABILITY OF EACH MODEL IN COMPLEX FLOWS OF INTEREST TO NASA AND THE AEROSPACE INDUSTRY. SECOND MOTIVATED BY THE CURRENT PRACTICE OF LARGELY OMITTING GRID CONVERGENCE STUDIES WHEN CONDUCTING WMLES WE PROPOSE TO SEEK A PROPER NOTION OF GRID-INDEPENDENT SOLUTION IN WMLES. CONDITIONS IN TERMS OF THE GRID RESOLUTION AND THE EXTENT OF THE WALL-MODELED REGION TO ACHIEVE CONVERGENCE IN LOW-ORDER STATISTICS WILL BE SOUGHT WITH THEIR IMPLICATION TO THE COST OF WMLES TAKING THE CONVERGENCE INTO CONSIDERATION. SHOULD THE NEED ARISE METHOD FOR CONDUCTING GRID-INDEPENDENT WMLES WITHOUT REACHING THE WALL-RESOLVED LIMIT WILL BE EXPLORED. THIS STUDY WILL HELP US TO ESTABLISH THE BEST PRACTICE TO PERFORM WMLES AND TO INTERPRET ITS RESULTS.

$583,940FY2020National Aeronautics and Space AdministrationNASA

Trustees Of The University Of Pennsylvania, The

Investigators

View source on USAspending →
THIS PROPOSAL TARGETS THE NRA ROA-2018 WITHIN THE TRANSFORMATIONAL TOOLS AND TECHNOLOGIES (TTT) PROJECT SUBTOPIC 2.1.2 ACCURATE AND EFFICIENT MODELS FOR SCALE RESOLVING SIMULATIONS. DESPITE ITS PROVEN PREDICTIVE CAPABILITY LARGE-EDDY SIMULATION (LES) HAS BEEN DEPLOYED RARELY FOR PRACTICAL EXTERNAL AERODYNAMICS APPLICATIONS DUE TO THE PROHIBITIVE COST INCURRED BY THE NECESSITY OF RESOLVING THE SMALL BUT ENERGETIC MOTIONS IN THE NEAR-WALL REGION OF HIGH REYNOLDS NUMBER TURBULENT FLOWS. NOVEL WALL-MODELING TECHNIQUES THAT HAVE EMERGED IN THE LAST DECADE HAVE THE POTENTIAL OF OVERCOMING THIS BARRIER BY NOT RESOLVING THE TINY NEAR-WALL EDDIES DIRECTLY BUT MODELING THEIR EFFECTS ON THE OUTER-LAYER FLOW. HOWEVER WALL MODELS HAVE NOT BEEN VALIDATED SUFFICIENTLY IN FLOWS EXHIBITING STRONG NONEQUILIBRIUM EFFECTS COMMONLY ENCOUNTERED IN AVIATION APPLICATIONS. IN ADDITION THE METHOD HAS BEEN USED WITH LITTLE ATTENTION ON HOW TO INTERPRET THE SOLUTION OBTAINED FROM SIGNIFICANTLY UNDERRESOLVED SIMULATIONS. THE PROPOSED RESEARCH WILL FOCUS ON EXTENDING THE APPLICABILITY OF WALL-MODELED LARGE-EDDY SIMULATION (WMLES) METHODOLOGIES TO COMPLEX NONEQUILIBRIUM FLOWS. WE PROPOSE TO DO TWO MAJOR TASKS TO ACHIEVE THIS GOAL. FIRST THE PREDICTIVE CAPABILITY OF THE WIDELY USED WALL MODELS WILL BE ASSESSED THOROUGHLY IN FLOWS EXHIBITING STRONG NONEQUILIBRIUM CHARACTERISTICS. THESE INCLUDE FLOW SEPARATION DUE TO MILD ADVERSE PRESSURE GRADIENT BOUNDARY LAYER WITH MEAN THREE DIMENSIONALITY AND CONVECTIVE HEAT TRANSFER UNDER PRESSURE GRADIENT. THIS WILL HELP US TO IDENTIFY THE RANGE OF APPLICABILITY OF EACH MODEL IN COMPLEX FLOWS OF INTEREST TO NASA AND THE AEROSPACE INDUSTRY. SECOND MOTIVATED BY THE CURRENT PRACTICE OF LARGELY OMITTING GRID CONVERGENCE STUDIES WHEN CONDUCTING WMLES WE PROPOSE TO SEEK A PROPER NOTION OF GRID-INDEPENDENT SOLUTION IN WMLES. CONDITIONS IN TERMS OF THE GRID RESOLUTION AND THE EXTENT OF THE WALL-MODELED REGION TO ACHIEVE CONVERGENCE IN LOW-ORDER STATISTICS WILL BE SOUGHT WITH THEIR IMPLICATION TO THE COST OF WMLES TAKING THE CONVERGENCE INTO CONSIDERATION. SHOULD THE NEED ARISE METHOD FOR CONDUCTING GRID-INDEPENDENT WMLES WITHOUT REACHING THE WALL-RESOLVED LIMIT WILL BE EXPLORED. THIS STUDY WILL HELP US TO ESTABLISH THE BEST PRACTICE TO PERFORM WMLES AND TO INTERPRET ITS RESULTS. · GrantIndex