OPTIMIZATION OF DIESEL INJECTION USING GRID COMPUTING

Miguel CaballerUniversidad Politécnica de Valencia

INTRODUCTION

• CaviGrid studies the fluid dynamics of the injection of turbo diesel engines.

• Multi-parametric studies of the geometry of the orifices of the cavity.

• Impact:– Reduction of fuel consumption by

tackling wider simulation configurations.

INTRODUCTION

Individual simulation features:CPU Time: ≈ 4-6 daysInput File: ≈ 10-100 MBMemory: RAM ≈ 2GB

HD ≈ 10GB

OPENFOAM

• Uses OpenFOAM tool:– Open Source tool.–Widely used Computational Fluid

Dynamics (CFD) software package.– Supports parallel execution:• MPI, OpenMP.

– Non-trivial installation.• A lot of dependencies .• Long and difficult compilation.

– Issues with different versions of GCC.

GRID SOLUTION

• Grid is used in the CaviGrid application to launch a set of multi-parametric simulations.

• It also can be used in any other OpenFOAM app.

• OpenFOAM save simulation results after a specified time steps.– It can be used as checkpoint data.– The results can be read before the whole

simulation ends.

GRID SCHEME

• Two steps:– Input file generation.• Specific for each application.• Create the OpenFOAM input files.• Upload them to an SE.

– Modify the relevant parameter for the experiment.– CaviGrid valuates the influence of the position of the

needle on the internal flow for different levels of injection pressure and a set of discharge pressures.

– Launch the set of jobs.• General for any OpenFOAM app.

OPENFOAM BINARIES

• Use a pre-packaged OpenFOAM file.– About 100 MB– Currently stored in a SE.• Can be stored in any accessible location

– All the apps and libraries needed.• It can be executed in (almost) any WN.

GRID JOB

1. Download OpenFOAM & the input file.2. If available it also downloads the last

simulation step stored in the SE.– In case of failure the job will start from

the last checkpoint available.– The user can access the SE to download

the available results.3. Launches the OpenFOAM solver in

background.4. Monitors the app and the simulation

steps saved into disk.5. Each simulation step saved is

packaged and uploaded to the SE in the same directory of the initial file.

Grid Job

SE

Monitor OpenFOAM

SimulationsData

CheckStatus

Save

Check Files

Upload Simulation

DataDownload

OpenFOAM &Input Data

Check &DownloadPreviousResults1 2

4

5

3

Check availableresults

DownloadResults

CAVIGRID SIMULATIONS

• Sequential multi-parametric simulations:– 5 different geometries– 2 levels of injection pressure – 2 sets of discharge pressures.

• A first set with 15 pressures for the first level of injection pressure • A second set with 4 pressures for the second level

of injection pressure – Total number of cases: 95

• More than one year of CPU time• Total output files: > 50 GB

CAVIGRID WMS SIMULATIONS TIMES

• Total response time for all the simulations:– ≈22 Days

• Problems found:– Slow CEs or CEs with too many queued jobs

• The WMS server does not make a good CE selection• Use white list of CEs

– Job Monitor developed• Script from UI• Cancel not running jobs

– For a long period of time• Resubmit the jobs

– Network issues 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 220

102030405060708090

100

Finished Jobs

Days

Jobs

CAVIGRID IN DIRAC

• Access more resources– Homogeneous access to different resources

• Grid & Cloud• CaviGrid has a model that fits better an IaaS.

– Can use pre-configured VMIs with OpenFOAM• Better Workload Management.

– Job Monitor will not be necessary.• Pilot Jobs:

– CaviGrid does not fit well with Pilot jobs• Too large jobs (4-6 days)

– Other OpenFOAM apps with smaller jobs can fit with Pilot Jobs:• Enable to reuse downloaded data for smaller jobs:

– OpenFOAM binaries– Input data files