Exploration of a horizontal confined impinging heated jet using both experimental and numerical methods

Impinging jets have been fascinating experimentalists and numerical modellers for many years with seemingly simple geometries revealing complex flow characteristics. Due to their high heat and mass transfer rates, impinging jets find wide use in engineering and industrial applications. Not only is the impinging jet interesting in isolation but it is often found as part of a more complex flow situation within an industrial setting. The dilemma for analysts under commercial pressure is always what level of detail is required for the results to be helpful but available in a reasonable time. The aims of this paper are: To understand a horizontal confined heated impinging jet using a combination of visualisation, experimental and numerical techniques. To understand the significance numerical modelling decisions can have in the context of an industrial setting. To make informed decisions about turbulence modelling dependent on the context of the flow problem

Use of computational fluid dynamics in domestic oven design

There is an increasing demand, both from customers and regulatory sources, for safer and more energy efficient products. Manufacturers are having to look to their design and development processes to service these demands. Traditional approaches have been to use prototype testing and only delve more deeply into specific aspects of the performance when issues arise. In this work the complex flow within the cooling circuit of the door of a pyrolytic oven is studied. A combination of Computational Fluid Dynamics (CFD) and experimental techniques is used. It will be shown that CFD can help with the achievement of an optimal solution, with the understanding of the flow behaviour and that there is a synergy between the numerical and experimental techniques. Using only one of these techniques would limit the understanding of the flow behaviour and could lead to a less than optimal solution to the design problem. This work aims to explore this particular complex industrial fluid flow situation to: understand the flow around the oven door’s cooling circuit  demonstrate the synergy of CFD and experimental work within development of a complex product explore the role of CFD within the product development process

Modeling of Surface Roughness for Flow Over a Complex Vegetated Surface

Abstract—Turbulence modeling of large-scale flow over a vegetated surface is complex. Such problems involve large scale computational domains, while the characteristics of flow near the surface are also involved. In modeling large scale flow, surface roughness including vegetation is generally taken into account by mean of roughness parameters in the modified law of the wall. However, the turbulence structure within the canopy region cannot be captured with this method, another method which applies source/sink terms to model plant drag can be used. These models have been developed and tested intensively but with a simple surface geometry. This paper aims to compare the use of roughness parameter, and additional source/sink terms in modeling the effect of plant drag on wind flow over a complex vegetated surface. The RNG k-ε turbulence model with the non-equilibrium wall function was tested with both cases. In addition, the k-ω turbulence model, which is claimed to be computationally stable, was also investigated with the source/sink terms. All numerical results were compared to the experimental results obtained at the study site Mason Bay, Stewart Island, New Zealand. In the near-surface region, it is found that the results obtained by using the source/sink term are more accurate than those using roughness parameters. The k-ω turbulence model with source/sink term is more appropriate as it is more accurate and more computationally stable than the RNG k-ε turbulence model. At higher region, there is no significant difference amongst the results obtained from all simulations. Keywords—CFD, canopy flow, surface roughness, turbulence models