Browsing by Author "Akowuah, Eric"

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    An Assessment of the impacts of selected Meteorological and Land Use Land Cover Datasets on the accuracy of wind speeds downscaled with the Weather Research and Forecasting Model for coastal areas in Ghana
    (Journal of Renewable Energies, 2024-06-27) Dzebre, Denis Edem Kwame; Asiedu, Charlotte; Akowuah, Eric; Boahen, Samuel; Amoabeng, Kofi Owura; Oppong, David
    Downscaling of wind speeds with the Weather Research and Forecasting model (WRF) model requires inputs from datasets such as Meteorological and Land Use and Land Cover (LULC) datasets. The accuracy of these datasets is among the factors that significantly impact the accuracy of the wind speeds that are generated by the model. In this study, we assess the accuracy of wind speeds data that are downscaled for an area in coastal Ghana using six meteorological, and two global Land use and Land Cover (LULC) datasets as inputs to the WRF model. In contrast to the LULC datasets tested, model wind speeds for the area were more significantly impacted by the different meteorological datasets. Meteorological datasets that were produced with higher resolution forecasts combined with more advanced data assimilation techniques produced better estimates of wind speed, and vice versa. The JMA JRA55 Reanalysis, NCEP GFS Analysis data, and ECWMF ERA5 gave the relatively best combinations of wind speed error metrics and are therefore recommended for consideration for downscaling of wind speeds for wind resources assessment in the coastal regions of Ghana. However, the ECWMF ERA5 is preferred as its mean error margins are fairly constant and so should be easier to correct.
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    Computational Modelling of Movement of Water Soluble Pollutants in the Soil
    (2011) Akowuah, Eric
    The thesis focuses on two dimensional modelling of water soluble pollutants through soil. Specifically, computational fluid dynamics (CFD) approach and adapted Navier-Stokes equations for porous flow are used to develop a code for flow of water soluble pollutants through fine sand. The code is used to simulate flow of water soluble pollutants in the soil within the laminar flow regime and to examine the distribution and dispersion of water soluble pollutants through soil layers. In developing the code, several flow equations and assumptions were considered and modified to suit the flow of water soluble pollutant through soil. Some of the equations incorporated in the simulation of the code include the Navier-Stokes equation, the Forchheimer equation and the Darcy’s velocity equation among others. In addition, the code makes use of several flow variables such as Reynolds number and pressure difference. The code was validated qualitatively using an experimental set-up to monitor the flow of dye within a square area filled with fine sand for three different dye sources. The distribution and dispersion pattern of the dye used was then physically examined at various times as simulated in the program and the results compared. It was found that the concentration of the dye decreased qualitatively away from the source. This is evident from the physical observation of the dye colour configuration obtained at the end of all the experiments as it faded in a decreasing manner away from the source but qualitatively increased in concentration with time. All the flow patterns of the experiments were comparable to the simulated results. The code may be used to approximate, interpolate and extrapolate the concentration level of pollutants as well as the distance and time a pollutant could travel from a source within a computational domain.