692 research outputs found
An efficient parallel immersed boundary algorithm using a pseudo-compressible fluid solver
We propose an efficient algorithm for the immersed boundary method on
distributed-memory architectures, with the computational complexity of a
completely explicit method and excellent parallel scaling. The algorithm
utilizes the pseudo-compressibility method recently proposed by Guermond and
Minev [Comptes Rendus Mathematique, 348:581-585, 2010] that uses a directional
splitting strategy to discretize the incompressible Navier-Stokes equations,
thereby reducing the linear systems to a series of one-dimensional tridiagonal
systems. We perform numerical simulations of several fluid-structure
interaction problems in two and three dimensions and study the accuracy and
convergence rates of the proposed algorithm. For these problems, we compare the
proposed algorithm against other second-order projection-based fluid solvers.
Lastly, the strong and weak scaling properties of the proposed algorithm are
investigated
HPC compact quasi-Newton algorithm for interface problems
In this work we present a robust interface coupling algorithm called Compact
Interface quasi-Newton (CIQN). It is designed for computationally intensive
applications using an MPI multi-code partitioned scheme. The algorithm allows
to reuse information from previous time steps, feature that has been previously
proposed to accelerate convergence. Through algebraic manipulation, an
efficient usage of the computational resources is achieved by: avoiding
construction of dense matrices and reduce every multiplication to a
matrix-vector product and reusing the computationally expensive loops. This
leads to a compact version of the original quasi-Newton algorithm. Altogether
with an efficient communication, in this paper we show an efficient scalability
up to 4800 cores. Three examples with qualitatively different dynamics are
shown to prove that the algorithm can efficiently deal with added mass
instability and two-field coupled problems. We also show how reusing histories
and filtering does not necessarily makes a more robust scheme and, finally, we
prove the necessity of this HPC version of the algorithm. The novelty of this
article lies in the HPC focused implementation of the algorithm, detailing how
to fuse and combine the composing blocks to obtain an scalable MPI
implementation. Such an implementation is mandatory in large scale cases, for
which the contact surface cannot be stored in a single computational node, or
the number of contact nodes is not negligible compared with the size of the
domain. \c{opyright} Elsevier. This manuscript version is made available
under the CC-BY-NC-ND 4.0 license
http://creativecommons.org/licenses/by-nc-nd/4.0/Comment: 33 pages: 23 manuscript, 10 appendix. 16 figures: 4 manuscript, 12
appendix. 10 Tables: 3 manuscript, 7 appendi
Computational fluid dynamics using Graphics Processing Units: Challenges and opportunities
A new paradigm for computing fluid flows is the use of Graphics Processing Units (GPU), which have recently become very powerful and convenient to use. In the past three years, we have implemented five different fluid flow algorithms on GPUs and have obtained significant speed-ups over a single CPU. Typically, it is possible to achieve a factor of 50-100 over a single CPU. In this review paper, we describe our experiences on the various algorithms developed and the speeds achieved
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