The application of numerical modelling in efficiency-driven designs: ventilation problem

The concept of Computational Fluid Dynamics (CFD) and its applications can be dated back as early as the 1960s. Over the years, due to the development of both theoretical research and computer technologies, CFD has become a very useful tool for design engineers and researchers for complex problems where manual calculation is neither sufficient nor possible.

This paper demonstrates a design example of a CFD application for ventilation problems in a greenhouse. Due to the forced air inflow and outflow by fans, turbulence was expected to form inside the greenhouse, which will affect the CO₂, H₂O and temperature distribution and ultimately impact the plant growth in certain areas of the greenhouse.

A 3D numerical model was developed in Ansys CFX to analyze this problem. This model is a multi-physics model that includes the simulation of dynamic flow distribution, heat transference and gas mixing. For accurate calculation of these three variables in the domain, three sub-models were created within the overall model and were two-way coupled to achieve integration. Various methodologies and techniques where applied to verify the model input and output, and different model sensitivity analysis scenarios were also discussed. Based on the simulation results, optimizations were implemented, which significantly improved the air circulation inside the greenhouse.

Although this paper is an example of a CFD application in the greenhouse, a similar methodology and concept have been applied in many other applications and other industries, which are listed at the end of this paper.