Mesh Effects for CFD Solutions
Sponsored by the Meshing, Visualization, and Computational Environments Technical Committee

15-19 June 2020
at the AIAA Aviation Forum and Exposition
Reno, Nevada, USA

GMGW
MVCE Working Group


Adam Clark
The Boeing Company

John Dannenhoffer
Syracuse University

Mark Gammon
ITI

Bill Jones
NASA Langley Research Center

James Masters
National Aerospace Solutions

Todd Michal
The Boeing Company

Carl Ollivier-Gooch
Univ. of British Columbia

Felix Rodrigo
Embraer

Nigel Taylor
MBDA UK Ltd

Hugh Thornburg
Engility

Carolyn Woeber
Pointwise


meshingworkshop@gmail.com

Mesh Effects for CFD Solutions: Overview

The AIAA Meshing, Visualization, and Computational Environments Technical Committee invites abstract submittals for a special session on Mesh Effects for CFD Solutions. The goal of this special session is to quantify how changes in the mesh affect solution accuracy and convergence for a CFD flow solver. Presentations from these special sessions will be used to update the gridding guidelines for future AIAA CFD workshops.

These special sessions will build upon the mini-symposium held at 2019's GMGW-2: Mesh Effects on CFD Flow Solutions.

All papers in these sessions will describe simulations on systematically varied meshes of a 2-D multi-element airfoil from the NASA High Lift CRM.

Not a Workshop - Submit Your Abstract to AIAA

Mesh Effects for CFD Solutions is not a workshop in the style of GMGW-1 and GMGW-2 for which special registration was required. Instead, it will consist of special sessions during the AIAA Aviation conference.

The normal AIAA process for submitting an abstract, review, acceptance, submission of a full manuscript, and presentation at the conference applies. For more details, see the AIAA Aviation 2020 Call for Papers.

IMPORTANT: After you submit your abstract to AIAA, email your control number and paper title to meshingworkshop@gmail.com so we can ensure it gets assigned to the special session.

Objectives

Participants in the special session are asked to perform a systematic investigation of what mesh characteristics constitute a best practice mesh for a 2-D multi-element airfoil for their flow solver using a Spalart-Allmaras (SA) or Spalart-Allmaras Negative (SA-Neg) turbulence model.

Papers should describe how the mesh was varied and correlate those mesh characteristics with solution accuracy and convergence.

The resulting best practice mesh should be documented in sufficient detail for another practitioner to replicate the results.

Examples of mesh characteristics that could be investigated:

  • Cell Type
  • Number of constant cell height mesh layers normal to wall
  • Stretching ratio normal to wall
  • Stretching ratio rate normal to wall
  • Edge length
  • Edge length ratio
  • Aspect ratio
  • Area ratio
  • Maximum included angle

Note that these examples are not required nor is this a comprehensive list. Feel free to choose characteristics or parameters that make sense for your meshing technology and flow solver.

Geometry

All participants in the special session are asked to use the supplied geometry below for their studies.

2-D HL-CRM multi-element airfoil
labeled schematic

  • The units in the geometry model files are meters.
  • The local chord (measured with the flap and slat stowed as shown above) is 1 meter.
  • The slat and flap deflection angles are 30 and 37 degrees, respectively.

A 2-D cut of the HL-CRM wing is provided in IGES and STEP formats. (Right click and use “Save link as”.)

Flow Conditions

Simulations should be run with the following flow conditions.

Mach Number 0.2
Reynolds Number 5 million
Cref 1.0
Angle of Attack 8 degrees
Viscosity 1.71e-5 kg/(m*2)
Ref Temp 272.1 K
Prandtl Number 0.72
Turbulent Prandtl Number 0.9
Heat Capacity Ratio 1.4
Freestream nu_t/nu for SA Model 3
Wall Boundary Condition Adiabatic
Farfield Boundary Condition Riemann Invariant
Farfield Distance 100 chord-lengths

Turbulence Models and Validation

A Spalart-Allmaras (SA) or Spalart-Allmaras Negative (SA-Neg) turbulence model is should be used for all simulations.

Your paper and presentation should note whether you have verified your implementation of SA or SA-Neg using the NASA Turbulence Modeling Resource.

Presentation and Deliverables

Participants are asked to include the following data in their paper and presentation.

  • Mesh size (cell and node counts)
  • Mesh spacing normal to wall
  • Cell stretching ratio
  • Plots for Cl, Cd, Cp, Cm, Cf (per element)
  • Use quarter chord (0.25 0 0) for the Cm reference point
  • Location of separated flow and stagnation points
  • Relevant a priori mesh metrics
  • Any error estimations or relevant solution metrics used in investigation

COMING SOON

A presentation template and further details on deliverables will be made available soon.