1. CFD Analysis of Buoyancy Driven Liquid Argon in MicroBooNe Cryostat Erik Voirin Fermilab Process Engineering Group Erik Voirin - Fermilab1MicroBooNe Buoyancy Driven Flow Analysis

2. Result Validation / Experience Code Validation – ANSYS CFX it arguably the top commercial CFD code, having passed many validation cases – My implementation of the code has passed validation cases for natural convection and Buoyancy driven flows Previous similar models – LBNE, LAPD, 35 ton (All LAr Natural Convection) Erik Voirin - Fermilab2MicroBooNe Buoyancy Driven Flow Analysis

3. Validation Case VALIDATION OF TURBULENT NATURAL CONVECTION IN A SQUARE CAVITY FOR APPLICATION OF CFD MODELLING TO HEAT TRANSFER AND FLUID FLOW IN ATRIA GEOMETRIES http://www.solarbuildings.ca/c/sbn/file_db/Doc_File_e/Validation%20of%20turbulent%20natural%20convection%20in%20a%20square%20cavity.pdf Erik Voirin - FermilabMicroBooNe Buoyancy Driven Flow Analysis3

4. Model Specifics 2D cross section analyzed (common practice) Liquid Argon @ 17.3 psia (properties from RefProp) – Molar Mass: 39.948 kg/kmol – Saturation Temperature: 88.877K – Density: 1385.6 kg/m 3 – Viscosity: 248.20 µPa*s – Thermal Conductivity:126.15 mW/m*K – Specific Heat: 1119.3 J/kg*K – Volume Expansivity: 0.0045182/K Erik Voirin - Fermilab4MicroBooNe Buoyancy Driven Flow Analysis

5. Model Specifics Fluid Model Physics: – Turbulence Model: k-omega and k-ε – Buoyancy Model: Boussinesq approximation – Turbulence Numerics:High Order – Advection Scheme: High Order – Convergence Criteria: 2.5e-5 Maximum Residual – Mesh: Hybrid Multi-Zone Quasi-2D – Double Precision: Utilized Erik Voirin - Fermilab5MicroBooNe Buoyancy Driven Flow Analysis

6. Field Cage in Cryostat Figure compliments of Bo Yu Erik Voirin - Fermilab6MicroBooNe Buoyancy Driven Flow Analysis

7. Two CFD Models 1. Fully enclosed field cage – All field cage boundaries modeled as impermeable steel plates – Conservative for temperature and boiling as walls restrict natural convection circulation 2. Realistically modeled field cage – Most accurate temperature and flow profiles – Much more difficult to converge Erik Voirin - Fermilab7MicroBooNe Buoyancy Driven Flow Analysis

8. Model Dimensions (Drawing from Bo Yu) Erik Voirin - Fermilab8MicroBooNe Buoyancy Driven Flow Analysis

9. Model Dimensions Erik Voirin - Fermilab9MicroBooNe Buoyancy Driven Flow Analysis

10. First Conservative (Enclosed) Model Erik Voirin - Fermilab10MicroBooNe Buoyancy Driven Flow Analysis

11. First Conservative (Enclosed) Model Erik Voirin - Fermilab11MicroBooNe Buoyancy Driven Flow Analysis

12. First Conservative (Enclosed) Model Erik Voirin - Fermilab12MicroBooNe Buoyancy Driven Flow Analysis

13. First Conservative (Enclosed) Model Erik Voirin - Fermilab13MicroBooNe Buoyancy Driven Flow Analysis

14. Model Dimensions (Drawing from Bo Yu) Erik Voirin - Fermilab14MicroBooNe Buoyancy Driven Flow Analysis

15. Model Dimensions Erik Voirin - Fermilab15MicroBooNe Buoyancy Driven Flow Analysis

16. Realistic Model Results Erik Voirin - Fermilab16MicroBooNe Buoyancy Driven Flow Analysis

17. Realistic Model Results Erik Voirin - Fermilab17MicroBooNe Buoyancy Driven Flow Analysis

18. Realistic Model Results Erik Voirin - Fermilab18MicroBooNe Buoyancy Driven Flow Analysis

19. Realistic Model Results Erik Voirin - Fermilab19MicroBooNe Buoyancy Driven Flow Analysis

20. Realistic Model Results Erik Voirin - Fermilab20MicroBooNe Buoyancy Driven Flow Analysis

21. Boundary Layer at Right Vertical Wall Calculated by Scalable Wall Functions Erik Voirin - Fermilab21MicroBooNe Buoyancy Driven Flow Analysis

22. No Steady State Solution These results are at one instance in time Turbulence causes unsteady behavior – Transient Analysis performed to observe this unsteady flow behavior Erik Voirin - Fermilab22MicroBooNe Buoyancy Driven Flow Analysis

23. Erik Voirin - Fermilab23MicroBooNe Buoyancy Driven Flow Analysis

24. Erik Voirin - Fermilab24MicroBooNe Buoyancy Driven Flow Analysis

25. Erik Voirin - Fermilab25MicroBooNe Buoyancy Driven Flow Analysis