[GTP] Joint GTP MMM Seminar -Dr. Orlando Ayala

[Silvia Gentile]

Methods and Issues for Highly-scalable Turbulence Simulations
Dr. Orlando Ayala
Department of Mechanical Engineering
University of Delaware

Wednesday August 3, 2011
NCAR Mesa Laboratory
1850 Table Mesa Drive
Chapman Room
Lecture 11:00am


Abstract:
Over the last 3 decades, direct numerical simulations (DNS) of 
homogeneous isotropic turbulence have served as a reliable quantitative 
research tool for studying the physics of small-scale turbulence and a 
variety of engineering and environmental applications where the dynamics 
of small-scale turbulence plays a critical role. Examples include 
small-scale vortex structures, scaling dynamics, turbulent mixing, 
particle dispersion, and collision-coalescence of cloud droplets. In 
almost all these applications, it is desirable to extend the range of 
scales or equivalently the flow Reynolds number so a more complete 
understanding of related physical processes can be obtained. While 
historically, the pseudo-spectral method is known to be the most 
accurate DNS approach, it has the challenge of performing global data 
communication (i.e., Fast Fourier Transform) which may not scale well on 
the state-of-the-art PetaScale computers with O(100,000) processors. 
Alternative approaches, such as high-order finite difference, 
finite-volume, and lattice Boltzmann equation, have been proposed to 
replace the pseudo-spectral method. The question I wish to address in 
this talk is:  how do different approaches compare in terms of accuracy 
and parallel efficiency? Complexity analyses of several approaches will 
be discussed and be used to understand scalability data obtained from 
several parallel computers. The simulated flows will also be compared to 
examine the resolution requirements for various approaches to achieve a 
comparable accuracy. Detailed implementation issues related to 
multi-dimensional domain decompositions and large-scale forcing scheme 
will be discussed.

Wednesday August 3, 2011
NCAR Mesa Laboratory
1850 Table Mesa Drive
Chapman Room
Lecture 11:00am

-- 
Silvia Gentile
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 803035
www2.image.ucar.edu/IMAGe