Task II Status:Papers,

Continued Research,Lessons Learned

N. Morley, S. Smolentsev, M-J Ni, R. Miraghaie, A. Ying, M. Abdou (UCLA)

Ramakanth Munipalli (Hypercomp)

J.C. Nave, S. Banerjee (UCSB)

Robert Woolley (PPPL

Synopsis of Recent Work in Task II

• Preparation of papers for FED special issue• Coordination of lab power upgrade for MTOR• J2 heat transfer experiment construction and

magnet design• FLIHY surface turbulence experiments visualizing

deformation cell size• Surface turbulence modeling with high

deformation starting higher Re runs• Channel flow MHD instability modeling• Continued HIMAG development and debugging

for parallel execution

Task II Papers Completed and Submitted for Review

“Thermofluid modeling and experiments for free surface flows of low-conductivity fluid in fusion systems”

by S.Smolentsev, N. Morley, B. Freeze, R. Miraghaie, J-C Nave, S. Banerjee, A. Ying, and M. Abdou

“Modeling of liquid metal free surface MHD flow for fusion liquid walls”

by N. B. Morley, S. Smolentsev, R. Munipalli, M.-J. Ni, D. Gao, and M. Abdou

Plus – contribution to an overview paper based on these two long papers has been given to Abdou, and input to Ying paper on MTOR experiments

E1 building to be torn down

Fusion Labspur trench with

2.5 MW of 12.47 KVAC New E1

power trench

UCLA fusion lab 2.5MW power upgrade piggy-backed of Nanotech building

project

J2 gap magnet design completed by PPPL

Designed to:

• reach uniform 2T in 15 x 15 cm x 100 cm gap

• allow access from top for visual diagnostics (LDV, PIV)

• utilize existing Rapid Technologies power supply

• have B g for open channel flow experiments

Surface turbulence studies for Flibe/Flinabe Liquid Walls

Variation of average free surface cell size as a function of Froude number (perpendicular)

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Key conclusion

Improvement of heat transfer is related to better mixing once the gravity effect is reduced

Free surface images (gray scale) taken directly via high speed imaging (4000 fps) along with analyzed images (right pairs) using image processing technique for Q=5 liters/sec and inclination angle of3.5

High surface deformation turbulence modeling pushing for higher Re

• Cases being run now include Re ~1000 at various inclination angles

• Need to finalize best cases for surface turbulence database

Re = 600 surface view as a function of time

Studies of MHD instability in closed channel LM flows

Distributions of basic quantities at Re=200, Rem=0.05, M=30, and =150: stream function (a), vorticity (b), velocity vectors (c), induced magnetic field (d), and near-wall vorticity (e). The white zones in the vorticity plot are the high vorticity regions with .

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• Triggered by spatially varying fields

• Looking at mixing promotion and threshold values

• Similar events seen in open channel flow

Flow direction

HyPerComp Incompressible MHD solver for Arbitrary Geometry

• Benchmarking and debugging of single processor level-set solution

• Benchmarking and debugging of parallel interfacial flow, and MHD flow problems

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Clockwise, from top left:

(a) First order reinitialization performed each time step,

(b) Performed every 5 steps, (c) Never performed, and(d) With Sussman-Fatemi source

terms to reduce mass loss errors

Modified level set technique to improve mass conservation

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2.5The broken dam problem with test data from Martin & Moyce, comparison with HIMAG.

Figure on left shows time history of the water column collapse

Validation against an unsteady free surface problem – Broken Dam

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Black line: using 6 processorsGreen line: using 4 processorsPink line: using 2 processors

Domain decomposition and computed result on 2,4,6 processors on the left

Interfacial flow simulation on multiple processors – Broken Dam

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Density = 1, Viscosity μ= 0.4 – 1.e-5σ = 1000B = (0,By,0), Where By = 1/(1 + exp(-x/0.15))

Wall BCs on constant y and constant z boundaries,U profile at inflow at x = -4 is: U(y,z) = (9/4)*(1-y*y)*(1-z*z) Outflow (x=4) BCs: d(V)/dn = 0., p = fixed (zero)Pressure : d(p)/dn = (jXB)n = σ*Bz*d(φ)/dx at walls Electric Potential:d(φ)/dn = 0 at the walls, = 0 at inflow, d(φ)/dn = V x B at outflow.

Test problem : based on Sterl [1990]

91x91 cells in the y-z plane,Total of 496,860 cells

Solved on 8 processors

Sample grid with 8 partitions for Ha = 10,000

Velocity carpet plot showing Hartmann layers and side-jets

Note that the wall layersare extremely sharp, and also well resolved

Pressure drop in high Ha flows

M-shaped velocity profiles for Ha = 1,000 and 10,000

1-(10000)-1/2 1-(1000)-1/2

Good agreement with standard sidelayer 1/Ha scaling

Inclusion of solution in conductingwall, Streamwise pressure drop

Needs to be compared and evaluated closely for accuracy

Benefits to complex problems such as: insulation with crack

At high Hartmann numbers, to simulate cracksin insulating coatings, it is often desired to clusteran enormous numbers of cells in the crack andwall layer regions. This number can frequentlyrun into several hundreds of thousand cells,and can approach a million cells even for relatively simple looking cases. Parallel processingis inevitable for such cases.

Future Development of HIMAG at Hypercomp

Possible funding sources for the immediate future to continue the development of HIMAG:

(a) Potential Phase-II SBIR activity: (starting June 2004 ? )

(b) Integration with ITER TBM program to ITER related work (effort to the level of about $ 100 K / year)

(c) Independent funding from DOE on super-computing initiatives,

Proposed work over next ~6 months

• Finalize papers based on reviews • Finish up experiments and DNS study of surface

turbulence with high deformation (UCLA and UCSB)• Continue HIMAG benchmark (Hypercomp and UCLA)

– Push high Hartmann no. limits in closed channels– Test against 3D interfacial MHD benchmark exps.– Application to MTOR NSTX exps and DIMES– Continue development of multi-material problems (including crack)

• Apply k-e MHD model to more advanced closed channel flow geometries – 3D MHD pipe flow

• Apply channel flow instability calculations to real cases, assess impact and prospect for continued work

• Oversee MTOR upgrades and J2 magnet

Blue indicates overlap into TBM program

Lessons learned in task II

• It takes a long time and dedication to do good (safe) experiments and develop and utilize sophisticated modeling codes

• Coordination is needed in fielding and continueing experiments - guidance and input from modeling and design.

• Not all experiments and codes end up working as planned (or when planned). Risk is an necessary element