8/10/2019 Parallel Computing Cfd

1/17

Parallel Computing in

CFD

L Sugumar

OE12S010

Department of Ocean Engineering

IIT Madras

8/10/2019 Parallel Computing Cfd

2/17

Contents

Introduction

Computer Memory Architectures

Parallel Programming Models

CFD

Computationally intensive task

Conclusion

References

8/10/2019 Parallel Computing Cfd

3/17

Introduction

Traditionally software has been written for serial

computation.

CPU executes the set of instruction one by one in

serial computation

8/10/2019 Parallel Computing Cfd

4/17

Parallel computing is the simultaneous use of

multiple compute resources to solve a

computational problem.

8/10/2019 Parallel Computing Cfd

5/17

Computer Memory Architectures Single Processor and memory(RAM)

Multiple Processor share same memory.

8/10/2019 Parallel Computing Cfd

6/17

Simple distributed memory architecture.

Hybrid distributed memory architecture.

8/10/2019 Parallel Computing Cfd

7/17

Parallel Programming Models

In software development considering thecharacteristics and capabilities of the hardware for

which the software is being build is vital.

Shared memory architecture OpenMP

Distributed memory architecture MPI

Hybrid distributed memory architecture-

(OpenMP + MPI)

8/10/2019 Parallel Computing Cfd

8/17

Serial code computation of 2 D steady state heat equation

8/10/2019 Parallel Computing Cfd

9/17

Parallel code computation of Laplace equation

in shared memory architecture.

8/10/2019 Parallel Computing Cfd

10/17

Parallel code computation of Laplace equation

in distributed memory architecture

8/10/2019 Parallel Computing Cfd

11/17

At the end of parallel computation one gets the same

temperature distribution contour as that of the serial

computation with substantial computational time reduction.

8/10/2019 Parallel Computing Cfd

12/17

What basically drives the CFD community to go behind

parallel computing?

Calculation of Lift and Drag of an Airfoil section in high speed

compressible flow( say transonic flow)

8/10/2019 Parallel Computing Cfd

13/17

Computational domain discretisationGrid generation

Big computational domain with fine grid

Far view of the grid Near view of the grid

8/10/2019 Parallel Computing Cfd

14/17

Can you guess many grid points are there in the above?

58500 grid points.

At Each grid points one has to solve

Mass continuity equation

XMomentum equation

Y- Momentum equation

Energy equation

Turbulence Equation, based on the turbulence model it can be

either one or two more equations.

So CFD is computationally intensive task and it needs a great

deal of memory, processing speed and storage capacity.

8/10/2019 Parallel Computing Cfd

15/17

High computational time and memory issue are the two

prime factors which basically drives the CFD community togo behind parallel computing.

Parallel computing is very fast, it saves time and money of

an organization.

Parallel computing is the future of the computing.

Conclusion

8/10/2019 Parallel Computing Cfd

16/17

References

Internet Parallel Computing Archive, wotug.ukc.ac.uk/parallel

Introduction to Parallel Computing,

www.llnl.gov/computing/tutorials/parallel_comp/#Whatis

Parallel Programming in C with MPI and OpenMP, Michael J.Quinn, McGraw Hill Higher Education, 2003

The New Turing Omnibus, A. K. Dewdney, Henry Holt and

Company, 1993

8/10/2019 Parallel Computing Cfd

17/17

Thank you