1. PRESENTATION OF CFD ACTIVITIES IN CV GROUP Daniel Gasser

2. What is CFD (1)? u CFD (Computational Fluid Dynamic) is a mean to simulate on computer a large range of phenomena linked to fluid mechanic : u flow analysis u heat transfer problems u thermodynamic u...

3. u Numerical resolution of equations governing fluid dynamic (conservation of mass, momentum and energy) u The main data required for a CFD analysis are u boundary and initial conditions u a mesh where physical values are calculated (velocity, pressure, temperature...) What is CFD (2)?

4. Goals of CFD studies in CV group u Get useful information about phenomena occurring in cooling and ventilation facilities (flow paths, head losses, heat transfer efficiency...). u Help in facilities design : pipe dimensioning, choice of a cooling fluid, shape improvement...

5. Current studies in CV group u Study of the bus bars cooling for ATLAS experiment. u Thermal analysis of an electronic box in the ECAL sub-detector (CMS experiment). u Cooling analysis of the ALICE experiment detector.

6. Cooling of the bus bar for ATLAS (context) u Compare the efficiency of air natural convection cooling with water cooling. u Choice of a simple cooling system.

7. Cooling of the bus bar for ATLAS ( 3D model)

8. Cooling of the bus bar for ATLAS (temperatures distribution) Air coolingWater cooling

9. Cooling of the bus bar for ATLAS (Heat transfer coefficient) Heat transfer to the cooling tubeHeat transfer to the air

10. Thermal analysis of an ECAL electronic box View of ECAL Electronic box

11. u Evaluate a proposed cooling solution which has to achieve the following requirements : u temperature variations of the crystal : 0.1 o C u crystal temperature of about 16 o C. u Analysis of the influence of the fin/box thermal contact resistance. Thermal analysis of an ECAL electronic box (context)

12. Thermal analysis of an ECAL electronic box (2D model)

13. Fin/box contact resistance of 2.75x10 -4 m 2 *K/W Fin/box contact resistance of 2.75x10 -2 m 2 *K/W Thermal analysis of an ECAL electronic box (temperature distribution)

14. Fin/box contact resistance of 2.75x10 -4 m 2 *K/W Fin/box contact resistance of 2.75x10 -2 m 2 *K/W Thermal analysis of an ECAL electronic box (temperature distribution below the thermal shield)

15. Cooling of ALICE detector u Evaluation of the solution proposed for the detector cooling. u The main requirement is a temperature gradient inside the detector of 3 o C.

16. Cooling of ALICE detector (model)

17. Cooling of ALICE detector (temperature distribution) Static model (no air flow)Air flow at 10000 m 3 /h and 20 o C

18. Cooling of ALICE detector (velocity field) Static model (no air flow)Air flow at 10000 m 3 /h and 20 o C

19. Conclusions u CFD helps to understand phenomena involved in situations where intuition or empirical calculations are useless. u CFD can reduce the number of test. u CFD is a cost and time saving tool if used adequately during the design process.