TSCVDC CFD Team Computational Fluid Dynamics at CERN

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TS/CV/DC CFD Team Computational Fluid Dynamics at CERN Michele Battistin CERN, Geneva - Switzerland

TS/CV/DC CFD Team Computational Fluid Dynamics at CERN Michele Battistin CERN, Geneva - Switzerland

Outline of Presentation • What is CERN? • CFD at CERN - Team &

Outline of Presentation • What is CERN? • CFD at CERN - Team & Resources - Main Applications • Casestudy Examples - 2 D Transient Study of ATLAS Detector - 3 D Steady-State Study of ALICE Detector www. cern. ch/cfd

What is CERN? • European Organisation for Nuclear Research • World’s largest physics centre

What is CERN? • European Organisation for Nuclear Research • World’s largest physics centre • Provides physicists the necessary tools to explore what matters is made of and what forces hold it together • Founded in 1954, it includes now 20 member states • Current activities concentrate on the construction of a particle accelerator and collider, the Large Hadron Collider (LHC) and detector experiments for it. www. cern. ch/cfd

How can we go back the time? 15 Billions of years ACCELERATOR ENERGY 1

How can we go back the time? 15 Billions of years ACCELERATOR ENERGY 1 Billion of years 330. 000 years 100 seconds 0. 1 Nanoseconds (10 -10) 10 -34 seconds PS (’ 59) LEP (’ 89) LHC (’ 07) 10 -43 seconds www. cern. ch/cfd

Accelerators and Detectors www. cern. ch/cfd

Accelerators and Detectors www. cern. ch/cfd

CFD at CERN Team & Resources • Part of the Technical Support Department, Cooling

CFD at CERN Team & Resources • Part of the Technical Support Department, Cooling and Ventilation Group, Detector Cooling Section; • 3 -5 young engineers (PJAS, FELL, Tech. Stud); • standard PCs for pre and post processing; • 20 Itanium® dual CPU 64 bit cluster connected with Infiniband®, Openlab (cern. ch/openlab), for parallel calculation (8 times faster since May 05); • 116 licenses available. Main Applications • Natural and Forced Convection Heat Transfer • Air and Water Cooling Systems • Safety Studies • Gas and Humidity Distribution www. cern. ch/cfd

Casestudy 1 2 D Transient Simulation of the Thermal Behaviour of the ATLAS Muon

Casestudy 1 2 D Transient Simulation of the Thermal Behaviour of the ATLAS Muon Chambers and Cavern www. cern. ch/cfd

Casestudy 1 - PROBLEM Ø The Muon Chambers and the Calorimeter dissipate a total

Casestudy 1 - PROBLEM Ø The Muon Chambers and the Calorimeter dissipate a total of 80 k. W of heat; Ø the cavern ventilation system: 60. 000 m 3/h of air at 17°C; 5 3 7 Ø to improve the cooling, thermal screens at 20°C can be installed in the inner layer of sectors 3, 5 and 7; Ø for operational reasons, temperature and velocity gradients must be minimised in regions around the detector. OBJECTIVE: To find the temperature and flow distribution around the detector www. cern. ch/cfd

Casestudy 1 – CFD MODEL Ø 2 D, time dependent simulation; Ø only the

Casestudy 1 – CFD MODEL Ø 2 D, time dependent simulation; Ø only the air region is modelled; Ø convection assumed as main mode of heat transfer Ø turbulence flow: standard k-ε for low Re; Ø buoyancy effect; Ø heat sources defined as heat fluxes; Ø cavern ventilation system taken into account; Ø ~230. 000 non-uniform hexahedral cells. www. cern. ch/cfd

Casestudy 1 - RESULTS Ø predicted temperature and velocity fields will be used in

Casestudy 1 - RESULTS Ø predicted temperature and velocity fields will be used in a more detailed thermal study of the muon chambers to be performed by RFNC-VNIITF – LLC Strela, Snezhinsk, Russia www. cern. ch/cfd

Casestudy 2 3 D Steady-State Natural Convection Study of the ALICE Dipole Magnet www.

Casestudy 2 3 D Steady-State Natural Convection Study of the ALICE Dipole Magnet www. cern. ch/cfd

Casestudy 2 - PROBLEM Ø The coils of the Dipole Magnet dissipate a total

Casestudy 2 - PROBLEM Ø The coils of the Dipole Magnet dissipate a total of 3. 46 MW of heat by Joule effect; Ø a water cooling system is designed to extract this heat; Ø insulation of the coils is not sufficient to prevent heat transfer to the surrounding environment; Ø for operational reasons, temperature inside the magnet must be within a specified limit. OBJECTIVE: To evaluate the overall heat loss from the coils, yoke and supports to air and the temperature www. cern. ch/cfd field around the magnet

Casestudy 2 – CFD MODEL Ø 3 D, steady-state simulation; Ø due to its

Casestudy 2 – CFD MODEL Ø 3 D, steady-state simulation; Ø due to its symmetry, only half magnet was modelled; Ø buoyancy driven flow; Ø model included solid parts (yoke and supports) and the surrounding air volume. The coils represented as empty volumes; Ø temperature and suitable heat resistance coefficients imposed on coils’ surfaces; Air Coil Yoke Supports Ø ~700. 000 tetrahedral cells. www. cern. ch/cfd

Casestudy 2 – RESULTS Air Temperature Distribution Around Magnet abc c b a Heat

Casestudy 2 – RESULTS Air Temperature Distribution Around Magnet abc c b a Heat Lost, k. W Coils Supports Yoke Convection 1. 7 1. 2 Radiation 1. 4 0. 4 -0. 7 Total to Air (half geometry) 3. 1 1. 6 0. 5 Total Heat Dissipated by the Dipole Magnet = 10. 4 k. W www. cern. ch/cfd