Classics in CFD

• R. Löhner, C. Othmer, M. Mrosek, A. Figueroa and A. Degro – Overnight Industrial LES for External Car Aerodynamics; AIAA-2020-2031 (2020). https://doi.org/10.2514/6.2020-2031
  • And we got there. Key technological breakthrough: Fast and accurate Cartesian solver with embedded grid solver.

• R. Löhner – Towards Overcoming the LES Crisis; Int. J. of Computational Fluid Dynamics 33,3, 87-97 (2019). DOI: https://doi.org/10.1080/10618562.2019.1612052
  • Yes, after 20 years of waiting we are getting there.

• R. Löhner – Improved Error and Work Estimates for High Order Elements; Int. J. Num. Meth. Fluids 72, 11, 1207-1218 (2013).
  • Somewhat controversial; it will be interesting to see what happens when the dust settles and cooler heads prevail…

• R. Löhner and A. Corrigan – Semi-Automatic Porting if a General Fortran CFD Code to GPUs: The Difficult Modules; AIAA-11-3219 (2011).
  • First large-scale production CFD code (with more than a dozen different solvers, hundreds of physics modules and more than a million lines of code) to run completely and efficiently on GPUs; key technological breakthrough: Python-based Fortran to CUDA translator

• A. Corrigan and R. Löhner – Porting of FEFLO to Multi-GPU Clusters; AIAA-11-0948 (2011).

• A. Loseille and R. Löhner – Anisotropic Adaptive Simulations in Aerodynamics; AIAA-10-0169 (2010).
  • First CFD run to compute accurately the sonic boom for an airplane flying at 11km height all the way to the ground; key elements: 3-D Euler, adaptation via local mesh modification

• Löhner, J.D. Baum, E. Mestreau, D. Sharov, C. Charman and D. Pelessone – Adaptive Embedded Unstructured Grid Methods; Int. J. Num. Meth. Eng. 60, 641-660 (2004).
  • A key idea, born in desperation (like so many), opening the way to simple embedded methods, which are now being used extensively in many fields

• O. Soto and R. Löhner – On the Computation of Flow Sensitivities From Boundary Integrals; AIAA-04-0112 (2004). (pdf)
  • If the cost function is defined on the boundary, and only the boundary moves, why is the domain required ?

• R. Löhner – Moore’s Law and the Diminishing Importance of Parallel Computing; Expressions of the IACM 13, 6-8 (2003).
  • As scientists, we are called to describe impartially what we see

• R. Löhner and M. Galle – Minimization of Indirect Addressing for Edge-Based Field Solvers; AIAA-02-0967 (2002).
  • And they said it was impossible…

• R. Löhner, C. Sacco, E. Onate and S. Idelsohn – A Finite Point Method for Compressible Flow; Int. J. Num. Meth. Eng. 53, 1765-1779 (2002).
  • First general FPM code for compressible code, combining: Delaunay and approximation-matrix based local cloud generation, Riemann solvers, limiters, edge-based data structures, shared-memory parallelization

• R. Löhner and E. Onate – An Advancing Point Grid Generation Technique; Comm. Num. Meth. Eng. 14, 1097-1108 (1998).
  • First general point generation technique

• R. Löhner, C. Yang and E. Onate – Viscous Free Surface Hydrodynamics Using Unstructured Grids; Proc. 22nd Symp. Naval Hydrodynamics Washington, D.C., August (1998).
  • First detailed EULER/RANS flowfield around an armada of ships

• J.D. Baum, H. Luo and R. Löhner – The Numerical Simulation of Strongly Unsteady Flows With Hundreds of Moving Bodies; AIAA-98-0788 (1998).
  • Never before had there been a simulation of a flowfield interacting with over 500 free-flying, contacting bodies in 3D (and comparison to experimental data)

• H. Luo, J.D. Baum and R. Löhner – A Fast, Matrix-Free Implicit Method for Compressible Flows on Unstructured Grids; J. Comp. Phys. 146, 664-690 (1998).
  • The combination of GMRES (as core solver) and LU-SGS (as pre-conditioner) produced a very fast (parallel, vector) and robust (RANS) solver

• J.D. Baum, H. Luo and R. Löhner, C. Yang, D. Pelessone and C. Charman – A Coupled Fluid/Structure Modeling of Shock Interaction with a Truck; AIAA-96-0795 (1996).
  • Most complex real-life 3-D fluid-structure problem at the time

• J.D. Baum, H. Luo and R. Löhner – Numerical Simulation of Blast in the World Trade Center; AIAA-95-0085 (1995).
  • Most complex 3-D transient geometry at the time
  • First unstructured grid run in CFD to approach 20 Million elements

• R. deFainchtein, S.T. Zalesak, R. Löhner and D.S. Spicer – Finite Element Simulation of a Turbulent MHD System: Comparison to a Pseudo-Spectral Simulation; Comp.Phys.Comm. 86, 25-39 (1995).
  • First real-life comparison of spectral and FEM codes for turbulent flows

• A. Shostko and R. Löhner – Three-Dimensional Parallel Unstructured Grid Generation; Int.J.Num.Meth.Eng. 38, 905-925 (1995).
  • First 2-D and 3-D parallel unstructured grid generators

• J.D. Baum. H. Luo and R. Löhner – Numerical Simulation of a Blast Inside a Boeing 747; AIAA-93-3091 (1993).
  • Most complex 3-D transient geometry at the time
  • First unstructured grid run in CFD to approach 8 Million elements

• R. Löhner, J. Camberos and M. Merriam – Parallel Unstructured Grid Generation; Comp.Meth.Appl. Mech.Eng. 95, 343-357 (1992).

• R. Löhner and J.D. Baum – Adaptive H-Refinement on 3-D Unstructured Grids for Transient Problems; Int.J.Num.Meth.Fluids 14, 1407-1419 (1992).
  • First efficient FEM use of 3-D adaptive H-refinement for highly transient problems
  • Full vectorization/auto-tasking efficiency
  • Basis of production codes FEFLO74, FEFLO96

• J.D. Baum and R. Löhner – Numerical Simulation of Shock Interaction with a Modern Main Battlefield Tank; AIAA-91-1666 (1991).
  • Most complex 3-D transient geometry at the time
  • First run to demonstrate the enormous usefulness of adaptivity for 3-D transient problems
  • First unstructured grid run in CFD to approach 2 Million elements

• R. Löhner – Three-Dimensional Fluid-Structure Interaction Using a Finite Element Solver and Adaptive Remeshing; Computer Systems in Engineering 1, 2-4, 257-272 (1990).
  • First demonstration of 3-D adaptive remeshing for transient problems
  • Basis of production codes FEFLO52, FEFLO54, FEFLO96

• R. Löhner and J. Ambrosiano – A Vectorized Particle Tracer for Unstructured Grids; J.Comp.Phys. 91, 1, 22-31 (1990).
  • First demonstration of fast tracking for unstructured-grid PIC codes

• R. Löhner, P. Parikh and C. Gumbert – Some Algorithmic Problems of Plotting Codes for Unstructured Grids; AIAA-89-1981-CP (1989).
  • First demonstration of fast plotting package for large 3-D unstructured grids
  • Basis of plotting codes FEPLOT, FEPOST, VPLOT and NASA’s FAST

• R. Löhner – Adaptive H-Refinement on 3-D Unstructured Grids for Transient Problems; AIAA-89-0365 (1989).

• R. Löhner – An Adaptive Finite Element Solver for Transient Problems with Moving Bodies; Comp.Struct. 30, 303-317 (1988).
  • First demonstration of 2-D adaptive remeshing for transient problems

• R. Löhner and P. Parikh – Three-Dimensional Grid Generation by the Advancing Front Method; Int.J.Num.Meth. Fluids 8, 1135-1149 (1988).
  • The 3-D advancing front grid generation paper
  • Basis of production codes FRGEN3D and VGRID

• R. Löhner – Some Useful Data Structures for the Generation of Unstructured Grids; Comm.Appl.Num.Meth. 4, 123-135 (1988).
  • First demonstration of fast grid generation with the advancing front method

• R. Löhner, K. Morgan, J. Peraire and M. Vahdati – Finite Element Flux-Corrected Transport (FEM-FCT) for the Euler and Navier-Stokes Equations; Int.J.Num.Meth.Fluids 7, 1093-1109 (1987).
  • The FCT paper for FEMs/unstructured grids
  • Basis of production codes FEFLO27, FEFLO28, FEFLO44, FEFLO64, FEFLO74, FEFLO96

• R. Löhner – An Adaptive Finite Element Scheme for Transient Problems in CFD; Comp.Meth.Appl.Mech.Eng. 61, 323-338 (1987).
  • First efficient FEM use of 2-D adaptive H-refinement for highly transient problems
  • Full vectorization
  • Basis of production codes FEFLO27, FEFLO28, FEFLO64

• R. Löhner, K. Morgan, J. Peraire and O.C. Zienkiewicz – Finite Element Methods for High Speed Flows; AIAA-85-1531-CP (1985).
  • This paper put Finite Element Methods for CFD on the map