Risk assessment in a damaged clean room by using the entropic Lattice Boltzmann method

• Entropic Lattice-Boltzmann method was used to simulate aerosol flows in complex geometries.
• Aerosol particles are very large compared with the air molecules and collisions between the particles and the air molecules are completely elastic.
• It is shown that the unstable pressure field can increase contamination level in the system.

Contamination risk factor (CRF) measures the effectiveness of clean room particle containment in preventing the airborne particles migration into a clean room from a corridor. This study describes the use of computer experiments to assess decontamination effectiveness of a barrier device such as a door to minimize particle migration rate. To this end, the air flow, which leaks out of the clean room through the gap of the door that is out of alignment, is simulated using the Lattice-Boltzmann method with the Bhatnagar–Gross–Krook (BGK) operator for collisions. The Knudsen number of the airborne particles is Kn~1, and they are in the transition regime. The blowing of airborne spherical particle in the corridor is simulated assuming that the forces experienced by a particle are a complex combination of interactions with individual gas molecules, and macroscopic interactions. It is shown that the misaligned door and uneven gaps along the edges induce an unstable pressure field. The unstable pressure results in an undesired air direction and increases the CRF level. This observation indicates that improper maintenance of a cleanroom can lead to contamination and a severe loss in end user product quality.