1. STUDY OF THE AIR TEMPERATURE AND VELOCITY AROUND THE ATLAS MUON CHAMBERS Emma Vigo Castellvi ST/CV Design

2. CONTENTS Situation of the Problem Solution methodology (CFD) Boundary Conditions The Previous Model The LMCh5 Model The Closed Model Conclusions Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

3. SITUATION OF THE PROBLEM Types: – BIS, BIL – BMS, BML – BOS, BOL Concerned by: – Temperature – Air velocities THE ATLAS BARREL MUON CHAMBERS Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

4. CONTENTS Situation of the Problem Solution methodology (CFD) Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

5. SOLUTION METHODOLOGY (CFD) CFD (Computational Fluid Dynamic) is a method allowing to simulate on computer a wide range of phenomena linked to fluid mechanic (flow analysis, thermodynamic, heat transfer...) Fluid mechanics equations numerically solved Domain splitted into cells Flow behaviour spatially uniform Physical gradients Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 cell+neighbours discretisation or mesh

6. THE MESH 100’000 elements Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

7. CONTENTS Situation of the Problem Solution Methodology (CFD) Boundary Conditions Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

8. THE UX15 VENTILATION SYSTEM BOUNDARY CONDITIONS Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

9. BOUNDARY CONDITIONS THE 2D “SECTION” Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

10. CONTENTS Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 Situation of the Problem Solution methodology (CFD) Boundary Conditions The Previous Model

11. Results: Quite optimistic Middle axis chambers: most solicitated Minor influence of the racks Problems: MDT’s heat load: 30mmW/channel Not distributed inlet THE PREVIOUS MODEL (LMCh3) Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

12. CONTENTS Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 Situation of the Problem Solution methodology (CFD) Boundary Conditions The Previous Model The LMCh5 Model

13. NEWS LMCh5 MODEL Heat load of the MDTs’ electronics Distributed inlet Transient calculation Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

14. BOUNDARY CONDITIONS LMCh5 MODEL Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

15. BOUNDARY CONDITIONS LMCh5 MODEL ( * ) corresponding to 65mW/channel Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

16. 6000sec : TEMPERATURE MAP LMCh5 MODEL

17. Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 6000sec : VELOCITY MAP LMCh5 MODEL

18. CONTENTS Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 Situation of the Problem Solution methodology (CFD) Boundary Conditions The Previous Model The LMCh5 Model The Closed Model

19. WHAT’S NEXT? Gaps between chambers: closed + porosity MCh: solids with conduction RPC’s non conducting heating surfaces Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 Status: - Geometry completely finished - Geometry successfully transferred to StarCD - At present: definition of new boundary conditions

20. CMCh MODEL Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

21. CONTENTS Situation of the Problem Solution methodology (CFD) Boundary Conditions The Previous Model The LMCh5 Model The Closed Model Conclusions Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

22. CONCLUSIONS Global understanding of the case study Velocity doesn’t reach high values Temperature gradients could be over the constraints Medium axis chambers: most solicitated being done Closed Muon Chambers (CMCh) study being done Next step Next step: 3D simplified model Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001

23. STUDY OF THE AIR TEMPERATURE AND VELOCITY AROUND THE ATLAS MUON CHAMBERS Emma Vigo Castellvi ST/CV Design Study of the Air Temperature and Velocity Around the ATLAS Muon Chambers Emma Vigo, ST/CV, 15 October 2001 See also: http://evigocas.home.cern.ch/evigocas/atlas_air_flow.html