Ventilation studies and simulations in cleanrooms

PROJECT DETAILS

• Clients: ICLOS
• Date: 2025
• Technology: CFD simulation

   

INTRODUCTION

This project analyses the airflow patterns and movement within a series of cleanrooms in a laboratory complex. The aim is to identify risks at the design stage in order to prevent areas of stagnant air or significant recirculation within the rooms. MSC Cradle’s ScStream software was used for the project.  

CFD MODELS

Firstly, we generate a geometry of the room based on the plans and data for the interior equipment of a size significant enough to interfere with the flow. We then configure the CFD model with the inlet and outlet conditions defined in the design, taking into account the flow balance designed for the ventilation system. We must also select a turbulence model that allows us to capture the phenomena of interest in the study with an appropriate mesh. Finally, we select the mesh to be used for the simulation. For this project, we used a Cartesian mesh, which offers significant computational advantages and allows us to define an appropriate level of refinement. The following image shows an overview of the mesh used:  

STUDY OF AIRFLOW IN CLEANROOMS

Once the models have been defined, we can calculate the various case studies by numerically solving the equations that describe air movement. Once the models have been calculated, we move on to obtaining the results during the post-processing stage. We first examine the velocity maps and streamlines obtained in the different rooms. In these cases, we want to ensure that the streamlines follow direct paths from supply to return, avoiding recirculation that could affect the work areas. Using the velocity maps, we also check that there are no areas with no air movement, where localised lack of air renewal could occur. We also use other metrics such as the intake index for each return, which allows us to identify which parts of the room each extraction unit draws air from, in order to assess whether the layout is appropriate. The image below shows an example of flow lines originating from one of the room’s supply vents, which we can use to study the behaviour of the air in that area.      

IDENTIFICATION OF CRITICAL AREAS: SMOKE TEST SIMULATION

Finally, we used a tracer visualisation to approximate the behaviour of each cleanroom during a harmless smoke test. This visualisation is extremely useful for predicting the outcome of a potential test and addressing any identified issues before carrying out the actual test. The following figure shows some images taken from the smoke test carried out via simulation in one of the cleanrooms: