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owen myles August 17, 2006 08:37

Modelling external flows; chimneys
Hello, can anyone recommend particular software for modelling external flows around buildings including flow through ducts. I want to simulate flows through a chimney (from multi-level apartments) and to compare the performance of various terminal devices (chimney cowls).


Owen Myles

Adrin Gharakhani August 17, 2006 15:52

Re: Modelling external flows; chimneys
Just curious exactly what you're looking for in terms of results. From the very brief description above it doesn't appear to me that you need an external flow code; unless, you want to see how smoke moves around buildings; in which case you don't really need to know exactly the flow inside the chimney is. Solving an entire system that includes inside the multilevel building and outside can be computationally expensive if you want correct results and not just nice color pictures. There has to be some modeling effort based on the true objective of the project, and then certain codes/methods are better than others depending on the objective.

Is this an industrial project or a class project, if you don't mind?

Adrin Gharakhani

owen myles August 18, 2006 04:45

Re: Modelling external flows; chimneys
Hello. Thanks for your response. I wish to calculate air flows in a 2 storey building and model accurately the pressure variations around an exhaust terminal. An objective is to see if adequate pressure differentials are available at each duct interface/obstruction to provide a minimum flowrate in each room using natural ventilation only. I also want to determine the effectiveness of different terminal devices in terms of their ability to provide high enough negative pressures. In simple terms I want to model two interconnected boxes attached to a vertical (circular) chimney with the "building" within an external flow field.

The exercise would be similar to modelling curtain wall ventilation systems as used in high rise heavily glazed offices (where air can be supplied from the curtain wall for heating in winter and discharged at higher velocity in summer to remove excessive heat).

Once I have completed some initial modelling, I will construct a scale-model of the system and perform experiments in a wind tunnel.

Renato. August 18, 2006 19:16

Re: Modelling external flows; chimneys
you could try out the Fire Dynamic Simulator (FDS). It's free and can be download from



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