Granted 200k to CFD-TPM JB On Tue, Jul 12, 2016 at 2:50 PM, Bair, Raymond A. <[email protected]> wrote:

This request for 200K looks OK.

Ray

----------------------------------------- Ray Bair Argonne National Laboratory

On 7/12/16, 2:22 PM, "[email protected] on behalf of [email protected]" <[email protected] on behalf of [email protected]> wrote:

Hello,

A change in allocation has been requested:

Requester: svegendla (Prasad Vegendla) Project: CFD-TPM Title: Computational Fluid Dynamics Modeling of Two-phase Boiling Flow and Critical Heat Flux Description: In boiling water reactors, dryout is an important limiting phenomenon in the design of heat exchangers and is associated with the disappearance of the liquid film on the wall in heat exchanger tube. A consequence of this non-wetting heated surface deteriorates the convective heat transfer mechanism resulting in a large rise in the wall temperature of heat flux imposed system such as nuclear reactor fuel rod assemblies. Since dryout is a hydrodynamic phenomenon involving entrainment and redeposition of droplets as well as boiling/evaporation of the liquid, the location of dryout is dynamic and its fluctuation may also give rise to thermal fatigue and corrosion. A large number of experimental and theoretical studies have been conducted over the past several decades to understand and quantify the processes leading to dryout in a heat exchanger tube.

* Nek5000 is a highly-scalable open-source transient CFD code developed by MCS-Argonne National Laboratory. This code is based on spectral element method and it is written in basic FORTRAN and C languages. It has more than 200 users world-wide and a long history of development, verification, and validation.

* In this project, Nek5000 is used as a platform to develop two-fluid model.

* In order to validate the Nek5000 development for two-phase boiling capability, several simulation runs are planned for wide range of pressure, mass flux and wall heat flux.

* In FY2015, blues allocated hours are efficiently used for projects of CFD-TPM, NE_RANS and SHARP-IF.

* A total of 4 members can use the allocated hours Current: undetermined amount Justification: Nek5000 is a highly scalable tool on fusion. NE users demonstrated good scalability up to several hundred cores. Recent simulations of homogeneous two-fluid boiling model on Fusion cores reported 10% and 58% overhead associated with MPI communication for 128 and 256 cores, respectively.

Requested: 200000

A specific reason has been given: To validate NEK5000 two-phase boiling code for multiple bench mark tests.

This needs to be approved and the final allocation amount decided upon.

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