Send mail to: mgnet@cs.yale.edu for the digests or bakeoff
mgnet-requests@cs.yale.edu for comments or help
Current editor: Craig Douglas douglas-craig@cs.yale.edu
Anonymous ftp repository: casper.cs.yale.edu (128.36.12.1)
ftp.cerfacs.fr (138.63.200.33)
World Wide Web: http://na.cs.yale.edu/mgnet/www/mgnet.html or
http://www.cerfacs.fr/~douglas/mgnet.html
Today's editor: Craig Douglas (douglas-craig@cs.yale.edu)
Volume 5, Number 11 (approximately November 30, 1995)
Today's topics:
Preprints by Zhang et al
Preprints by Pasciak et al
Papers by Shapira
UG Software available
CFD short course
Book by D'yakonov
Faculty opening at CU-Denver
Faculty opening at Virginia Tech
Updated preprint by Douglas
-------------------------------------------------------
Date: Mon, 20 Nov 1995 13:53:32 -0500
From: Jun Zhang
Subject: Preprints by Zhang et al
An Accurate and Stable Multigrid Method
for Convection-Diffusion Equations
Murli M. Gupta, Jules Kouatchou and Jun Zhang
Department of Mathematics
The George Washington University
Washington, DC 20052, USA
Abstract:
We introduce a high-order compact difference scheme with multigrid algorithm
to solve the convection-diffusion equations with constant coefficients. This
high-order discretization scheme is shown to be more accurate and stable than
the usual five-point discretization scheme. It solves the convection-
diffusion equations directly without using any preconditioner or adding any
artificial dissipation terms. This method is shown to converge faster than
some of the existing methods and to achieve higher accuracy. Numerical
experiments are presented to validate the conclusions.
Editor's Note: in mgnet/papers/Gupta-Kouatchou-Zhang/con_diff.ps.gz and
------------- mgnet/papers/Gupta-Kouatchou-Zhang/con_diff.abs.
Acceleration of Five-point Red-Black Gauss-Seidel
in Multigrid for Poisson Equation
Jun Zhang
Department of Mathematics
The George Washington University,
Washington, DC 20052, USA
Abstract:
A new relaxation analysis and two acceleration schemes are proposed for the
five-point Red-Black Gauss-Seidel smoothing in multigrid for solving two
dimensional Poisson equation. For a multigrid V cycle, we discovered that
under-relaxation is applicable to restriction half cycle and over-relaxation
is applicable to interpolation half cycle. Numerical experiments using
modified multigrid V cycle algorithms show that our simple acceleration
schemes accelerate the convergence rate by as much as 34% with negligible
cost. This result is contrary to the existing belief that SOR is not suitable
for using as a smoother in multigrid for Poisson equation, because the gain in
computational savings would not pay for the cost of implementing it. More
important is the idea of employing different parameters to accelerate the
reduction of low and high frequency errors separately. Our discovery offers a
new way for SOR smoothing in multigrid.
Editor's Note: in mgnet/papers/Zhang/sor.ps.gz and
------------- mgnet/papers/Zhang/sor.abs.
-------------------------------------------------------
Date: Mon, 6 Nov 1995 08:47:05 -0500
From: pasciak@jep.das.bnl.gov (Joe Pasciak)
Subject: Preprints by Pasciak et al
I put the papers and abstracts into incoming/pasciak. Some of these papers
are not necessarily directly multigrid related but all have something to do
with preconditioning so they may be of some interest to members of the net.
Joe
Editor's Note: I moved all 7 of the new contributions to the directory
------------- mgnet/papers/Pasciak-et-al.
-------------------------------------------------------
Date: Tue, 14 Nov 1995 22:05:44 -0700
From: Yair Shapira
Subject: Papers by Shapira
I put one more paper on mgnet. I also put an updated version of
the paper tlanalysis.ps.gz. Please put them in mgnet/papers/Shapira.
Improved Black Box Multigrid
for Definite and Indefinite Problems
Yair Shapira
Computer Science Department, Technion, Haifa 32000, Israel
e-mail: yairs@lanl.gov.
Abstract
A two-level analysis method for certain separable problems is introduced.
Unlike standard two-level analysis methods, based on Fourier analysis, it is
based on spectral analysis, hence applicable to non-normal problems and to
certain problems with variable coefficients. It motivates the definition of
improved versions of Black Box Multigrid for diffusion problems with
discontinuous coefficients and indefinite Helmholtz equations. For
anisotropic problems, it helps in choosing suitable implementations for
frequency decomposition multigrid methods. For highly indefinite problems, it
provides a way to choose a suitable mesh size for the coarsest grid used.
Numerical experiments confirm the analysis and show the advantage of the
present methods.
Editor's Note: in mgnet/papers/Shapira/bbox.ps.gz and
------------- mgnet/papers/Shapira/bbox.abs.
update is mgnet/papers/Shapira/tlanalysis.ps.gz.
-------------------------------------------------------
Date: Mon, 27 Nov 1995
From: Peter Bastian
Subject: UG Software available
Dear colleagues,
we are happy to announce the availability of version 3.1 of our software "UG"
(short hand for Unstructured Grids).
UG is a flexible software library for the development of adaptive multigrid
methods on unstructured meshes. The main idea of UG was to implement most parts
in a problem-independent way, so that the software can be reused for many
different applications.
The main features of the problem-independent part are:
* 2D (triangles, quadrilaterals) and 3D (tetrahedra) unstructured meshes
* tree-based local refinement and coarsening
* user-definable number of degrees of freedom in nodes, edges, faces and
elements (conforming, non-conforming and mixed finite-elements can be
implemented)
* BLAS and iterative methods (smoothers, multigrid, cg)
* powerful script language
* Multi-window graphical user interface for X11 and Macintosh. No special
graphics libraries required
* 1000 pages of documentation (man-pages, postscript)
* Parallel version with reduced functionality available (2D, degrees of
freedom only in nodes, dynamic load balancing, interfaces for PVM, NX,
PARIX, T3D, MPI)
Applications in the current distribution include:
* 2D scalar diffusion equation with linear conforming and nonconforming
finite-elements
* 2D linear elasticity with conforming and non-conforming finite-elements
* 2D incompressible, stationary Navier-Stokes equations
* 3D convection-diffusion equation
Many other applications are currently being developped on the basis of UG.
UG is available for free for all non-profit organizations. For further
information use:
* World Wide Web: http://www.ica3.uni-stuttgart.de/~ug
* FTP: ftp.ica3.uni-stuttgart.de/pub/ug/ug3.1
* email: ug@ica3.uni-stuttgart.de
Editor's Note: I put a copy in mgnet/Codes/ug (version 3.1.2) at both Yale
------------- and CERFACS.
-------------------------------------------------------
Date: Fri, 10 Nov 1995 09:04:21 -0700
From: cliu@carbon.cudenver.edu (Chaoqun Liu)
Subject: CFD short course
ADVANCES IN COMPUTATIONAL FLUID DYNAMICS
A 5-Day Short Course Announcement
Louisiana Tech University, Ruston, Louisiana
June 24 - 28, 1996
The Louisiana Tech University will host a 5-day CFD short course
in the summer of 1996. A number of leading researchers will give lectures
on recent advances in CFD. Several advanced teaching and research codes
for incompressible flow, direct numerical simulation for flow transition,
and numerical combustion with detailed chemistry will be described and
distributed to all attendants for free.
Anyone who is interested in CFD and has basic multigrid and CFD
knowledge, including faculty, graduate students, scientific researchers,
government agents, and industrial scientists and engineers,
are welcome to attend. The registration fee is at a
discounted level of $350 (group rate is $250 and student rate is $150),
and it covers all lecture notes, floppy disks with computational codes,
a reception, and a formal dinner.
The lectures include:
Multigrid and multilevel adaptive methods
First-order system least square (FOSLS)
Preconditioning for low speed flow
Central difference, R-K scheme, and residual smoothing
Boundary conditions for time dependent flows
Upwind differencing - principles and recent development
Advanced turbulence models
Fast Navier-Stokes solver
High-order grid generation
Direct numerical simulation for complex geometry
Non-reflecting outflow boundary condition
Multilevel grid dissipation
Numerical simulation for turbulent combustion with detailed chemistry
Numerical pollutant prediction
The speakers include:
Dr. L. Sakell (US Air Force Office of Scientific Research)
Dr. A. Brandt (Weizmann Institute, Israel)
Dr. E. Turkel (Tel Aviv University, Israel)
Dr. P. Roe (University of Michigan)
Dr. S. McCormick (University of Colorado at Boulder)
Drs. T-H Shih and J. Zhu (NASA Lewis Research Center)
Dr. C-H Sung (Navy David Taylor Research Center)
Dr. C. Liu ( Louisiana Tech University)
Drs. Z. Liu, X. Zheng, and C. Liao ( Louisiana Tech University)
If you are interested in this short course, please fill
out the attached form and email it back to cliu@math.latech.edu or
send it by regular post to:
Prof. Chaoqun Liu
ACFD Short Course Chair
Department of Mathematics and Statistics
Louisiana Tech University
P.O. Box 3189, Ruston,
LA 71272-0001
Tel : (318) 257-2538
Fax : (318)257-3935
email : cliu@math.latech.edu
http://www.math.latech.edu/~cliu
For more information please go to:
http://www.math.latech.edu/~cliu
or call Dr. Chaoqun Liu at (318) 257-2924.
________________________________________________________________________
Name _______________
Mailing Address :
_____________________________________________
_____________________________________________
_____________________________________________
Day Phone Number : __________________________
Fax Number: __________________________
Email Address : __________________________
I am interested in the ACFD short course. Please send me the
-------------------------------------------------------
Date: Tue, 21 Nov 95 16:05:53 +0300 (MSK)
From: dknv@cmc.msk.su (dknv)
Subject: Book by D'yakonov
Dear Craig, I am pleased to inform you that CRC Press published my book "
Optimization in Solving Elliptic Problems" (about 600 pages) a few weeks ago.
They did an excellent job and it seems that the book is not superexpansive
(about 80 $). It is possible to contact the Orders department directly by
e-mail (orders@crcpress.com) . I am asking you to pass the information to
other interested people at your "vicinity".
Best wishes. Gene D'yakonov.
-------------------------------------------------------
Date: Thu, 2 Nov 1995 18:02:04 -0700
From: aknyazev@tiger.cudenver.edu (Andrew Knyazev)
Subject: Faculty opening at CU-Denver
University of Colorado at Denver
Department of Mathematics
The Department of Mathematics at the University of Colorado
at Denver is seeking to fill two tenure-track positions at
the rank of Assistant Professor, beginning August 1996.
Positions are contingent on budgetary approval. We offer
B.S., M.S. and Ph.D. degrees with optional focus in one
of six areas: computational mathematics, discrete
mathematics, engineering mathematics, operations research,
probability, and statistics. These also comprise active
areas of research of our resident faculty.
Applicants are expected to show strong potential for
research and teaching and have a commitment to professional
service. Applicants must have, or expect to receive by next
August, a Ph.D. in mathematics or a related discipline. In
general, we seek qualified applicants in one of the focus
areas and prefer someone who can interface with two or more
areas. For these positions, the areas of greatest interest
are applied probability or statistics, and computational
mathematics. However, we shall consider applications with
another focus in applied mathematics.
To apply, please send a current vita, list of publications,
a statement of research plans and goals, a statement of
teaching philosophy, and arrange to have three letters of
recommendation sent to:
Burt Simon, Search Committee Chair
Mathematics Department - Campus Box 170
University of Colorado at Denver
P.O. Box 173364
Denver, CO 80217-3364
Our fax number is 303-556-8550. For more information on
our department and university visit our web site at
http://www-math.cudenver.edu. We will begin screening
applications December 15, 1995.
The University of Colorado at Denver is committed to
enhancing the diversity of its administration, faculty and
staff, and to program access for persons with disabilities,
and invites and strongly encourages nominations of and
applications from women, members of ethnic and racial
minorities, veterans, and people with disabilities.
Alternative formats of this ad or job description are
available upon request.
-------------------------------------------------------
Date: Mon, 20 Nov 1995 09:39:49 -0500
From: Christopher Beattie
Subject: Faculty opening at Virginia Tech
We posted this on nanet a few weeks ago but want to make sure we have
healthy representation of multigrid types in our applicant pool.
Virginia Polytechnic Institute and State University
Department of Mathematics
Applications are solicited for a tenure-track assistant
professorship in numerical analysis. Candidates must have
a PhD in mathematics or equivalent, with a strong record
or demonstrated potential in research and teaching. We seek
candidates who will augment an existing faculty focus in
numerical treatment of PDEs, optimization, and computational
linear algebra.
Send a letter of application, curriculum vitae, summary
of research plans, together with four letters of recommendation
(one of which addresses teaching skills), to:
Numerical Analysis Search Committee,
Department of Mathematics,
Virginia Tech,
Blacksburg, VA 24061-0123.
Review of applications will begin on December 20, 1995
and will continue until the position is filled.
Virginia Tech has a strong commitment to the principle of diversity
and, in that spirit, seeks a broad spectrum of candidates including
women, minorities, and people with disabilities. Individuals with
disabilities desiring accommodations in the application process should
contact Christopher Beattie, Department of Mathematics, 540-231-6536
(TDD/PC 1-800-828 1120- Voice 1-800-828-1140).
-------------------------------------------------------
Date: Mon, 27 Nov 1995 08:08:08 -0500
From: Craig Douglas
Subject: Updated preprint by Douglas
A Review of Numerous Parallel Multigrid Methods
Craig C. Douglas
IBM T. J. Watson Research Center
Yale University Computer Science Department
CERFACS
Abstract
Multigrid methods originated earlier this century, in the personnel computing
era. Someone who needed to compute an approximation to the solution of a
partial differential equation during that era would fill a room with people.
After using very simple mechanical calculators to compute parts of the
approximation, these people would pass their parts to the other people in the
room who needed them. Except for the very different time scales and
approximate solution accuracy, this process is similar to computing on today's
distributed memory parallel computers.
Parallel multilevel methods are shown to be the natural precursors to standard
multilevel methods based on the personnel computing era of earlier this
century. They are also the natural successors to standard multilevel methods
in the age of computers. What makes six parallel multilevel methods practical
and impractical is discussed in the context of the three algorithms that
encapsulate them.
Appears in slightly edited form in SIAM News, V.25, N.3, May, 1992.
This will appear in
Applications on Advanced Architecture Computers
Edited by Greg Astfalk
Available spring 1996
Approx. 350 pages
Softcover
ISBN 0-89871-368-4
List Price $35.00
SIAM Member Price $28.00
Order Code OT53
Editor's Note: in mgnet/papers/Douglas/para-mg.ps.gz and
------------- mgnet/papers/Douglas/para-mg.abs.
------------------------------
End of MGNet Digest
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