Gas reservoirs with low permeability (k<0.1 mD) are among the unconventional reservoirs and are commonly termed as "Tight Gas Reservoirs". In conventional gas reservoirs that have high permeability, the flow of gas is basically controlled by the reservoir permeability and it is calculated using the Darcy equation. In these reservoirs, gas flow due to gas diffusion is ignored compared to Darcy flow. However, diffusion phenomenon has a significant impact on the gas flow in tight gas reservoirs and the mechanism of gas diffusion can no longer be ignored in comparison to Darcy flow. In this study, a dual mechanism based on Darcy flow as well as diffusion is used for the gas flow modeling in tight gas reservoirs. The diffusivity equation is obtained using this method that it indicates the gas flow in a porous media. The conventional dry gas pseudo pressure function is not able to linearize the diffusivity equation including diffusion effect. Subsequently, a new real gas pseudo pressure function is used and a novel real gas pseudo time function is introduced. These pseudo functions consider changes in gas properties with pressure and linearize the diffusivity equation. The linear diffusivity equation is solved analytically for constant gas flow boundary condition under Pseudo Steady State (PSS) situation. Then, pseudo Steady state analytical solution, based on new functions of pseudo pressure and pseudo time, is obtained. The calculation of reservoir parameters such as permeability, effective diffusion coefficient and original gas in place (OGIP) using reservoir data is the first application of analytical solution. Reservoir data is required to analysis the results of application of introduced model in low permeability gas reservoir.

An existing operational trisonic wind tunnel is upgraded to improve its performance criterion in the transonic regime. In this research, the test section is modified according to the operational requirements of the various existing transonic wind tunnels. Several perforated walls are designed, manufactured, and installed on the top and bottom sides of the test section. The flow in the test section of the wind tunnel is surveyed for the empty condition prior to testing models. Once satisfactory results regarding the flow quality requirements in the test section under various conditions were achieved, a 2D model, NACA 0012, and a 3D standard model for the transonic wind tunnels, AGARD-B, are manufactured and tested under various conditions for the purpose of integral calibration and validation of the tunnel data. Surface pressure distribution as well as the force and moment data compare well with the existing data from other tunnels for similar models tested under the same conditions.

The meshless local Petrov-Galerkin method with unity as the weighting function has been applied to the solution of the Navier-Stokes and energy equations. The Navier-Stokes equations in terms of the stream function and vorticity formulation together with the energy equation are solved for a driven cavity flow for moderate Reynolds numbers using different point distributions. The L2-norm of the error as a function of the size of the control volumes is presented for different cases; and the rate of convergence of the method is established. The results of this study show that the proposed method is applicable in solving a variety of non-isothermal fluid flow problems.

Three-dimensional RANS simulations are employed numerically to study flow characteristics around a near-wall circular cylinder for varying gap-to-diameter (G/D) ratios (Where G is the gap between the cylinder and the wall and D is the cylinder diameter) and at Reynolds numbers from 100 to 3900.Pressure distribution around the circular cylinder, base pressure magnitude, separation and stagnation angles, force coefficients and Strouhal numbers were calculated and compared for all of the cases. Inception of vortex shedding can be seen when a sudden decrease in the maximum of positive pressure coefficient occurs. Vortex shedding mechanism and possibility of suppression further investigated via comparison of swirling strength in upper and lower vortex regions through parameter L which signifies vortical activity and balance with respect to the wake center-line and also the flow type parameter, l, representing the extensional strain dominance in the wake flow and gap flow. Vortex shedding suppression observed for the cases with the high unbalance vorticity content in the vortex regions, namely for L³2.

We prove the existence of Steady 2-dimensional flows, containing a bounded vortex, and approaching a uniform flow at infinity. The data prescribed is the rearrangement class of the vorticity field. The corresponding stream function satisfies a semilinear elliptic partial differential equation. The result is proved by maximizing the kinetic energy over all flows whose vorticity fields are rearrangements of a prescribed function.

The length of the Steady Gradually Varied flow (G.V.F) profile in a circular gravity pipe section is computed using the Graphical Integration Method. The equations used for the solution are: a) the dynamic equation of Gradually Varied flow in a prismatic channels, b) the hydraulic exponents M and N equation derived by Chow [2], and c) the Varied hydraulic exponents M (y/do) and N(y/do) equation modified by Zaghloul [15]. The results of the calculated G.V.F profile length using the modified hydraulic exponents M(y/do) and N(y/do) equation are closer to the G.V.F length calculated based on the exact formulation of the G.V.F dynamic equation. The percentage difference ranges from 0.67% to 8.72% for various bed slopes and G.V.F depth limits. The calculated G.V.F profile length using the Chow hydraulic exponents M and N resulted in wider values with percentage difference ranges from 0.16 to 25.59%. Hence, a remarkable improvement of the computation of G.V.F profile is achieved using the modified M(y/do) and N(y/do) hydraulic exponents.The unSteady Gradually Varied flow wave propagation in circular gravity pipe section is simulated using the Explicit Method. The Extended Transport block (EXTRAN) of the latest Storm Water Management Model (PCSWMM2000) was used to route the wave through a circular gravity pipe section. The resulting routed hydrographs by the Explicit Method and the EXTRAN Block of the PCSWMM 2000, provided similar flow peak and lag time in both cases.A computer package was developed for the Steady G.V.F length calculation for gravity pipes using the Microsoft Excel spreadsheet. The results are plotted using the Excel graphics capabilities.A second computer package using Microsoft Excel was developed for the UnSteady G.V.F simulation based on the Explicit Method. The routed hydrographs arc plotted by the Excel graphics capabilities.The Excel packages for the Steady and UnSteady G.V.F are user friendly and are posted on the Internet Website location http://briefcase.yahoo.com/civil engineering2001.ARead me File is provided for each Excel package and is used as a users guide.