Many parts of sub-Saharan Africa, hydrogeologic data are sparse and difficult to access. One example is the Nigeria geological formations including other countries geological history like Keta Basin of southeastern Ghana and the Coastal Sedimentary Basin of Togo. Existing data quality on groundwater flow patterns and hydrodynamic aquifer characteristics from this region is weak, and subsurface geology is poorly understood in many parts of the region. In the present study, hydrochemistry and isotope geochemistry are applied to obtain hydrogeological information from the area in spite of lack of basic data on groundwater flow patterns and aquifer characteristics.1-4 In regard to permeability predictions,2,4 that some researchers that modified the Kozeny - Carman equation to better represent sediment mixtures by incorporating their fractional packing model for porosity.3 Measured porosity and permeability on sediment mixtures and then compared these to values predicted by the models mentioned above. These mixtures were model approximations of natural poorly-sorted sands and sandy gravels. The introduction of five possible types of packing that can occur in a sediment mixture accounts for complex packing arrangements that may be present naturally. Therefore5,6 assumed that the expanded fractional packing model is generally representative of poorly-sorted sands and sandy gravels. The present study will evaluate how well the model applies to natural sediment. Taking the results and procedures of7 into account6,7 focused further on the permeability of bimodal sediment mixtures by taking measurements at small support scales.3 Revising the air-based permeability procedures of other experts7 is to reduce displacement of sediment by air slip-flow.3 determined a sufficient depth in the sediment at which a stable representative measurement could be taken, which he termed the tip-seal burial method. He also improved upon the correction needed for the air-based measurements to account for the effects of high-velocity flow. He repeated the permeability measurements taken by7,8 and further confirmed the applicability of the permeability model.3,7,9 it was found that the air-based measurements corresponded well to the water-based measurements for both sand mixtures and sand/pebble mixtures. Thus, the air-based measurements with a small support scale were generally similar to the water based measurements with a larger support scale,5,6 it is concluded that the permeability of bimodal sediment mixtures of poorly-sorted sands can be accurately measured with the air-based permeameter. He found that mixtures dominated by finer grains show only subtle differences between air- and water-based measurements.5,10 determined that the air-based permeameter captures subtle changes in poorly sorted sands better than in pebbly sands. In addition to previous,4,6,7 studies it has been conducted since in the work of some researchers9,10,12 that utilize models for predicting permeability.11-13 presented a permeability model for bimodal sediment mixtures that is based on parameters that separate pore throat porosity from total porosity and the effective radius from the total radius of the grains,2 developed permeability model using representations of the grain size distribution as well as the petrophysical properties of porosity, volume fraction of fines, and bulk density. Other research on the porosity-permeability relationship for porous media involved the modification of previous models.1,3,5,7 These studies all use different models for predicting permeability but none of them utilize a fractional packing model for porosity. Model sediment mixtures and predicted porosity values are useful tools for testing the applicability of a permeability model. Therefore, the research conducted by some researchers11,12 that provides results that can be applied to other permeability models. This study will take the necessary step of testing his model to determine if it is accurate for natural sediment, which will help improve confidence in its applicability.10,13
The Implicit Scheme Numerical Solution
(1)
But
Velocity, v in meter per second (m/s), and porosity [-].
Thus equation (1) becomes:
(2)
Converting the PDE to its algebraic equivalent equation by applying the finite different approximation technique for the implicit scheme, we obtain as follows.
(3)
(4)
(5)
Substituting equation (3) through (5) into (2) gives:
nu
Or
(6)
For cases where the initial and final conditions are given, boundary condition at the first node can be expressed as:
(7a)
Hence, first node equation is expressed as:
(7b)
Similarly, the last node boundary condition is:
(8a)
(8b)
For
; and for the first instance, we obtain as follows:
:
,
(9a)
,
(9b)
,
(9c)
,
(9d)
,
(9e)
,
(9f)
,
(9g)
,
(9h)
,
(9i)
Arranging equations (6a) through (6i) in vector matrix gives:
Where:
Hence, at any point with time, the general form of the above equation is presented as: