CIBSE YEN CFD Presentation. Joseph Berthoud

Transcription

1 CIBSE YEN CFD Presentation Joseph Berthoud 10 th May 2017

2 Introduction 20 Minutes / 40 Slides What is CFD Validation Jobs Physical Scale Modelling Questions Page 2

3 Introduction Nearly 20 years experience. Maths with Theoretical Physics (M.Sci.) Tunnel ventilation (road, rail, stations) Wider Ventilation, Wind, Water 16 modellers (both DTM & CFD) in AECOM London 2 x 128-core clusters Page 3

4 CFD How does it work

5 Introduction Desktop Study Simple computer study Detailed computer study Scale model validation Typical Uses Wind Water HVAC Fire Pollution Page 5

6 How Does It Work But what s it for? Page 6

7 How Does It Work Purpose Appropriate for its intended use Sensitivity Validation Level of accuracy required Conservative or realistic? Page 7

8 How Does It Work Navier Stokes equations = well known and look simple Page 8

9 How Does It Work Navier Stokes equations Unsolved (Millennium prize) Approximate process UNSOLVED Page 9

10 How Does It Work Page 10

11 How Does It Work - Geometry Geometry from Architect/Engineer (Surrounds from LiDAR) Hand rebuilt for appropriateness Complete? Level of detail? Certainty? Page 11

12 How Does It Work - Mesh 3D space divided into 10 million or more cubes (or tetrahedra) Great care needed to put small cubes where important things happen Page 12

13 How Does It Work - Mesh High gradients, e.g. Diffusion of jets Important information Reporting close to walls Both Water surface Page 13

14 How Does It Work - Apply Physics Velocities Temperatures Roughness Radiation Page 14

15 How Does It Work - Apply Physics Inlet/outlet conditions Pressure/Flowrate Fluid height Roughness Page 15

16 How Does It Work - Solution CFX, Fluent, Star-CCM Open Foam FDS, AutoCAD, etc. etc. Iterations Convergence Page 16

17 How Does It Work Results Page 17

18 How Does It Work - Results Volume Fraction Page 18

19 How Does It Work - Results Velocity Pressure Streamlines Page 19

20 How Does It Work - Results Visibility Page 20

21 How Does It Work Calculations & Reporting Page 21

22 Validation

23 Validation Validation undertaken against: Simple analytical solutions Published research papers Laboratory measurements Laboratory videos Page 23

24 Validation Page 24

25 Validation Page 25

26 Validation Page 26

27 Validation Page 27

28 Validation Page 28

29 Validation Validating the engineer? If you re doing it, get it thoroughly checked and reviewed by experienced colleagues. If not, put in all the cautionary words you need. If you re commissioning it, get a CFD expert to review it. Page 29

30 Jobs

31 Jobs HVAC Page 31

32 Jobs HVAC Page 32

33 Jobs Facades Page 33

34 Jobs Thermal Bridging Page 34

35 Jobs Exhaust Tracking Page 35

36 Jobs Hydraulics Page 36

37 Jobs Fire Page 37

38 Jobs Structural Interaction Page 38

39 Scale Models and CFD

40 Advantages of each method Scale Models Turbulent gusting Lots of data, (but only for discrete points) Quick changes, but have to set up model first Computer Models Quick and Dirty possible Results everywhere Design iterations 3D flow visualization Page 40

41 Mixed Working Computer models for design advice and options Then CFD and scale models for validation Page 41

42 Thank You 25 th May 2016