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RPI Boiling model for mcirochannel

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Old   April 21, 2022, 15:18
Default RPI Boiling model for mcirochannel
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Suraj A Bolaj
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Hi there,
We are performing analysis on rectangular microchannel
Geometry: 40mm long x 0.24mm wide x 0.5mm height

Working Fluid: Water-liquid and water-vapour
Models:-
Multiphase: Eulerian, RPI boiling model
Energy equation: on
Viscous: k-epsilon, RNG, Standard wall functions, mixture.

Boundary Conditions: temp=323k, Inlet velocity=0.826m/s at 1 bar pressure
Outlet(pressure outlet): water liquid(temp=373.15), water vapour(temp=373.15)

3 sides wall heated(copper wall) heat flux=500kw/m^2 (bottom, left, right walls), top wall(polycarbonate Laxen) heat flux=0

Methods:-
Scheme: Coupled
Gradient: Least squares cell-based
Pressure: Second order
Momentum: Second order upwind
Volume fraction: QUICK
Turbulent Kinetic Energy: Second order upwind
Turbulent Dissipation Rate: Second order upwind
Energy: Second order upwind

During Initialization I am facing an error indicating the Turbulent viscosity ratio is limited to e5 in cells..... and as the calculation proceeds the cells reduces

after 500 iterations I got this error:
Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...
Stabilizing pressure coupled to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Divergence detected in AMG solver: pressure coupled Stabilizing k to enhance linear solver robustness.

Divergence detected in AMG solver: k Stabilizing epsilon to enhance linear solver robustness.

Divergence detected in AMG solver: epsilon Stabilizing temperature to enhance linear solver robustness.
Stabilizing vof-1 to enhance linear solver robustness.

Divergence detected in AMG solver: vof-1
Error at host: floating point exception

Error at Node 0: floating point exception

===============Message from the Cortex Process================================

Compute processes interrupted. Processing can be resumed.

================================================== ============================

Error: floating point exception
Error Object: #f
Registering ReportDefFiles, ("C:\Users\91960\Desktop\Major project\rectangular channel\tough assignment_files\dp0\FLU\Fluent\mass-flow-rate-rfile.out" "C:\Users\91960\Desktop\Major project\rectangular channel\tough assignment_files\dp0\FLU\Fluent\report-file-0.out")

Error: WorkBench Error: Could not handle event: SolutionStatusUpdate
Error Object: #f

Calculation complete.

Can anyone help me with this?

Thank you
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Old   April 29, 2022, 06:27
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Neeraj Kumar Vidhyarthi
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multiphase model should be used here is homogenous
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Old   January 24, 2024, 10:07
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marcus aurelius
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What is homogeneous model?

I still have fundamental question, can we use RPI wall boiling model for microchannels where the width can be as small as 0.2 mm?
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eulerian multiphase model, fluent, microchannel, rpi model, rpi wall boiling


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