Simple Load Balancing for Chemically Reacting Flows

2018 ◽  
Author(s):  
Rainald Lohner ◽  
Fumiya Togashi ◽  
Joseph D. Baum
Keyword(s):  
Load Balancing ◽  
Reacting Flows ◽  
Chemically Reacting Flows ◽  
Chemically Reacting

Load balancing for chemically reacting flows

2017 ◽  
Vol 27 (12) ◽  
pp. 2768-2774
Author(s):  
Rainald Löhner ◽  
Fumiya Togashi ◽  
Joseph David Baum
Keyword(s):  
Load Balancing ◽  
Parallel Machines ◽  
Reacting Flows ◽  
Reacting Flow ◽  
Processing Unit ◽  
Content Type ◽  
Central Processing ◽  
Chemically Reacting Flows ◽  
Extreme Load ◽  
Chemically Reacting

Purpose A common observation made when computing chemically reacting flows is how central processing unit (CPU)-intensive these are in comparison to cold flow cases. The update of tens or hundreds of species with hundreds or thousands of reactions can easily consume more than 95% of the total CPU time. In many cases, the region where reactions (combustion) are actually taking place comprises only a very small percentage of the volume. Typical examples are flame fronts propagating through a domain. In such cases, only a small fraction of points/cells needs a full chemistry update. This leads to extreme load imbalances on parallel machines. The purpose of the present work is to develop a methodology to balance the work in an optimal way. Design/methodology/approach Points that require a full chemistry update are identified, gathered and distributed across the network, so that work is evenly distributed. Once the chemistry has been updated, the unknowns are gathered back. Findings The procedure has been found to work extremely well, leading to optimal load balance with insignificant communication overheads. Research limitations/implications In many production runs, the procedure leads to a reduction in CPU requirements of more than an order of magnitude. This allows much larger and longer runs, improving accuracy and statistics. Practical implications The procedure has allowed the calculation of chemically reacting flow cases that were hitherto not possible. Originality/value To the authors’ knowledge, this type of load balancing has not been published before.

Three-dimensional upwind, parabolized Navier-Stokes code for chemically reacting flows

10.2514/3.261 ◽  
1991 ◽  
Vol 5 (3) ◽  
pp. 274-283 ◽  
Author(s):  
Philip E. Buelow ◽  
John C. Tannehill ◽  
John O. levalts ◽  
Scott L. Lawrence
Keyword(s):  
Three Dimensional ◽  
Reacting Flows ◽  
Navier Stokes ◽  
Chemically Reacting Flows ◽  
Chemically Reacting

Upwind parabolized Navier-Stokes code for chemically reacting flows

10.2514/3.157 ◽  
1990 ◽  
Vol 4 (2) ◽  
pp. 149-156 ◽  
Author(s):  
John C. Tannehill ◽  
John O. Ievalts ◽  
Philip E. Buelow ◽  
Dinesh K. Prabhu ◽  
Scott L. Lawrence
Keyword(s):  
Reacting Flows ◽  
Navier Stokes ◽  
Chemically Reacting Flows ◽  
Chemically Reacting

Numerical Simulation of Heat Transfer and Fluid Dynamics in Supersonic Chemically Reacting Flows

2010 ◽  
Author(s):  
Alexander M. Molchanov ◽  
Anna A. Arsentyeva
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
High Speed ◽  
Stokes Equations ◽  
Order Approximation ◽  
Reacting Flows ◽  
Supersonic Combustion ◽  
Special Method ◽  
Chemically Reacting Flows ◽  
Chemically Reacting

An implicit fully coupled numerical method for modeling of chemically reacting flows is presented. Favre averaged Navier-Stokes equations of multi-component gas mixture with nonequilibrium chemical reactions using Arrhenius chemistry are applied. A special method of splitting convective fluxes is introduced. This method allows for using spatially second-order approximation in the main flow region and of first-order approximation in regions with discontinuities. To consider the effects of high-speed compressibility on turbulence the author suggests a correction for the model, which is linearly dependent on Mach turbulent number. For the validation of the code the described numerical procedures are applied to a series of flow and heat and mass transfer problems. These include supersonic combustion of hydrogen in a vitiated air, chemically reacting flow through fluid rocket nozzle, afterburning of fluid and solid rocket plumes, fluid dynamics and convective heat transfer in convergent-divergent nozzle. Comparison of the simulation with available experimental data showed a good agreement for the above problems.

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