Loomans Bouw 2002 - Modelling techniques 5 PARTICLE...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
PARTICLE CONCENTRATION CALCULATIONS USING CFD - A COMPARISON - Marcel Loomans and Tony Lemaire TNO Building and Construction Research, P.O.Box 49, 2600 AA Delft, The Netherlands Tel. +31 – 15 – 269 5248, Fax. +31 – 15 – 26 5300 [email protected], www.tno.bouw.nl Summary Three approaches for the calculation of the particle contaminant distribution in a room using CFD are described. The approaches are tested for two types of flow problems. The results indicate that the Euler approach, in which only the particle settling velocity is incorporated, presents an attractive alternative for the more precise Lagrange approach. The Passive Scalar approach should not be used when calculating the particle distribution in a room. Introduction The use of CFD for the calculation of the exposure of persons to airborne particles (carcinogenic, biological; particle diameter (D p ) in the order of 0.3 – 20 P m) in a room gains interest as legislation on this subject becomes more strict. In this paper options to calculate particle concentrations in a room, using CFD, are discussed. A comparison is made between three approaches: the Passive Scalar (Gaseous), the Euler and the Lagrange approach. This comparison is made within the context of the development of a measurement protocol for bioaerosol measurements. The measurement location in the room is one of the items that are addressed in this protocol. The three approaches are compared for two types of flow problem. The first comparison uses particle measurement results from literature for cleanroom ventilation conditions. The second one uses new measurement results obtained from bioaerosol measurements in an office room. The latter measurements have been performed within the context of the above described protocol development. Methodology The main difference between the three approaches to calculate the contaminant distribution in a room lies in the complexity with which individual particles are tracked in the flow. The Passive Scalar and the Euler approach deal with the particles as if it where a gas. In the Euler approach however the gravity force that acts upon a particle is included in the calculation of the particle contaminant distribution. The Lagrange approach not only includes the gravity force, but all other possible forces that may act upon a particle. It calculates individual particle trajectories instead of a bulk of particles. From the individual particle trajectories the contaminant distribution can be derived. The most important difference between the Passive Scalar and the Euler approach and the Lagrange approach therefore is that inertial effects are only dealt with in the Lagrange approach. The other two approaches assume that a particle will follow the flow instantly. Inclusion of the gravity in the Euler approach is
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/06/2010 for the course PHAST 1 taught by Professor Donck during the Spring '10 term at École Normale Supérieure.

Page1 / 4

Loomans Bouw 2002 - Modelling techniques 5 PARTICLE...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online