Dan Nørtoft Sørensen

Modelling flow and heat transfer around a seated human body by computational fluid dynamics

A database (http://www.ie.dtu.dk/manikin) containing a detailed representation of the surface geometry of a seated female human body was created from a surface scan of a thermal manikin (minus clothing and hair). The radiative heat transfer coefficient and the natural convection flow around the manikin were calculated using computational fluid dynamics. Results were compared to published data and to measurements by particle image velocimetry. The agreement was generally good and variations across the manikin well predicted. The uniqueness of the present work is twofold: (1) the geometry of the computational manikin has all surface features of a human being; (2) the geometry is an exact copy of an experimental thermal manikin, enabling detailed comparisons between calculations and experiments.

Modeling-gas phase reactions in indoor environments using computational fluid dynamics

Abstract This CFD modeling study examines the concentrations of two gaseous compounds that react in an indoor setting to produce a hypothetical product. The reactants are ozone and either d-limonene or α-terpinene (which reacts with ozone about 40 times faster than d-limonene). In addition to two different terpenes, the scenarios include two air exchange rates (0.5 and 2.0 h −1 ). The terpene is introduced as a floor source with an emission pattern similar to a floor-care product. These four scenarios have been set in a fairly large two-dimensional room (13.6×40.6 m ) with a supply at the top of the left wall and an exhaust at the bottom of the right wall. The room has been deliberately scaled so that the Reynolds numbers for key flow regimes match those of a room in which the calculated flow field has been validated against measured data. It has been further assumed that ozone interacts with room surfaces while the terpenes do not. The results show that for all four scenarios, under steady-state conditions, there are large concentration gradients within the room for both reactants and product. To some extent this is due to imperfect mixing. However, it also reflects that reactions occur at different rates across the room (because of varying reactant concentrations) and that the time available for reactions to occur varies with the room location (because the “age of the air” varies from point to point). Locally, within the room, the concentrations calculated by the CFD method differ significantly from those calculated by a one-compartment mass-balance model assuming perfect mixing.

Trienylfuranol A and trienylfuranone A–B: metabolites isolated from an endophytic fungus, Hypoxylon submoniticulosum , in the raspberry Rubus idaeus

A strain of Hypoxylon submonticulosum was isolated as an endophyte from a surface-sterilized leaf of a cultivated raspberry (Rubus idaeus). The liquid culture extract displayed growth inhibition activity against Saccharomyces cerevisiae using a disc diffusion assay. The extract’s major component was identified as a new natural product, trienylfuranol A (1S,2S,4R)-1-((1′E,3′E)-hexa-1′,3′,5′-trienyl)-tetrahydro-4-methylfuran-2-ol (1), by high-resolution LC-MS and 1D and 2D NMR spectroscopy. Two additional new metabolites, trienylfuranones A (2) and B (3), were isolated as minor components of the extract and their structure elucidation revealed that they were biosynthetically related to 1. Absolute stereochemical configurations of compounds 1–3 were confirmed by NOE NMR experiments and by the preparation of Mosher esters. Complete hydrogenation of 1 yielded tetrahydrofuran 7 that was used for stereochemical characterization and assessment of antifungal activity.