Post on 26-Mar-2018
MetNet MeetingPoznań, 11th October 2010
Computer Fluid Dynamics (CFD)In Civil Engineering
Fabian Cybichowski, Ph. D. Eng.
MetNet MeetingPoznań, 11th October 2010
Presentation TOC:
1) Introduction: what is CFD?
2) Example 1: air flow in a room.
3) Example 2: flow and heat transfer in a duct.
4) Conclusions.
MetNet MeetingPoznań, 11th October 2010
”Computational fluid dynamics (CFD) is one of the branches of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows”
(Wikipedia)
Popular techniques:- RANS (Reynolds Averaged Navier-Stokes)- LES (Large Eddy Simulations)- DNS (Direct Numerical Simulations)
Most common discretization methods:- FVM (Finite Volume Method)- FEM (Finite Element Method)
MetNet MeetingPoznań, 11th October 2010
CFD – aeronautics & car industry
MetNet MeetingPoznań, 11th October 2010
CFD – urban planning
MetNet MeetingPoznań, 11th October 2010
CFD – fire simulations
MetNet MeetingPoznań, 11th October 2010
CFD – HVAC, IAQ
MetNet MeetingPoznań, 11th October 2010
Example 1
Ventilation in a room
MetNet MeetingPoznań, 11th October 2010
Example 1: geometry
MetNet MeetingPoznań, 11th October 2010
Example 1: geometry & mesh
MetNet MeetingPoznań, 11th October 2010
Example 1: boundary conditions
- Steady, viscous flow- Uniform temperature (without
heat exchange)- Non-slip condition on the walls,
standard wall functions- Standard k-ε model- Air enters the room through the
vent just under the ceiling and leaves through the opening under the doors
MetNet MeetingPoznań, 11th October 2010
Example 1: results(stream lines)
- The ventilation efficiency is not satisfactory, most of the air goes directly from air vent to the opening under the doors
- Problems with IAQ can be expected
MetNet MeetingPoznań, 11th October 2010
Example 1: modified model(stream lines)
- Air vent moved to the short wall
- Now the fresh (clean) air sweeps entire room
- The comfort of a person working at the desk should be improved
MetNet MeetingPoznań, 11th October 2010
Example 2
Air flow through a duct, with heat exchange
MetNet MeetingPoznań, 11th October 2010
Example 2: geometry
- Roof panel with embedded air ducts for free-cooling & solar energy absorption
MetNet MeetingPoznań, 11th October 2010
Example 2: geometry & mesh
MetNet MeetingPoznań, 11th October 2010
Example 2: boundary conditions
- Steady, viscous flow- Constant temperature of air entering the duct- Constant temperature of three upper walls (exposed to the sun)- No heat exchange on the bottom plane (thermal insulation)- No slip condition on the walls, standard wall functions- Standard k-e model
MetNet MeetingPoznań, 11th October 2010
Example 2: results (animation)
MetNet MeetingPoznań, 11th October 2010
Example 2: results
MetNet MeetingPoznań, 11th October 2010
Conclusion
CFD modeling in civil engineering: - is very convenient in terms of geometry and boundary conditions, offers
much more flexibility then laboratory experiments –some quantities are simply impossible to measure,
- gives a great amount of data about the simulated process and offers high data resolution,
- require vast knowledge of both the phenomena and numerical simulations,- can easily yield poor results – hence the need for careful validation
of every simulation.
It is great when it works, but not easy to perform: still rather research than engineering tool.
MetNet MeetingPoznań, 11th October 2010
Conclusion
CFD modeling in civil engineering: - is very convenient in terms of geometry and boundary conditions, offers
much more flexibility then laboratory experiments –some quantities are simply impossible to measure,
- gives a great amount of data about the simulated process, also very high data resolution,
- require vast knowledge of both the phenomena and numerical simulations,- can easily yield poor results – hence the need for careful validation
of every simulation.
It is great when it works, but not easy: still rather research than engineering tool.
Thank you for
your attention