Simulation of the Scalar Transport above and within the Amazon Forest Canopy

The parallelized large-eddy simulation model (PALM) was used to understand better the turbulent exchanges of a passive scalar above and within a forested region located in the central Amazon. Weak (2 ms−1) and strong (6 ms−1) wind conditions were simulated. A passive scalar source was introduced to the forest floor for both simulations. The simulations reproduced the main characteristics of the turbulent flow and of the passive scalar transport between the forest and the atmosphere. Noteworthily, strong and weak wind conditions presented different turbulence structures that drove different patterns of scalar exchange both within and above the forest. These results show how passive scalar concentration is influenced by the wind speed at the canopy top. Additionally, higher wind speeds are related to stronger sweep and ejection regimes, generating more intense plumes that are able to reduce the passive scalar concentration inside the forest canopy. This work was the first that used PALM to investigate scalar transport between the Amazon rainforest and the atmosphere.

Numerical Investigation of the Capture Efficiency of a Domestic Range Hood

Comfort criteria in building are increasing continuously. Multiple studies tend to use CFD approaches in order to predict and optimize the flow conditions accurately. One of the most relevant problematic is the extraction of the CO2 by kitchen hoods. In the present work, a new solver, based on a buoyancy Boussinesq solver and a turbulent passive scalar transport equation, is developed in OpenFoam to model the heated CO2 extraction by a rotating fan using the Multiple reference frame (MRF) approach. The new solver is first validated successfully against experimental results of a heated cavity and CO2 diffusion. An improvement of 30% in the capture efficiency is reached by increasing the extraction flow rate of the fan from 100 to 300 cfm. An extraction efficiency of 100% is observed for flow rates above 330 cfm. The novelty of this study is to present a new open-source solver able to model the rotation of the whole fan, CO2 transport and heat exchange simultaneously in steady state.