The stably stratified flow in a linearly heated vertical pipe filled with a fluid-saturated porous medium is studied. We have emphasized the impact of permeability (via Darcy number, Da) as well as Prandtl number (Pr) on the stability of basic flow at the different azimuthal modes of disturbances (n = 0, 1). The stability of basic flow is examined for a wide range (0.01, 100) of Pr, which comprises different types of fluids (i.e., mercury, gas, liquid, and heavy oils). The extensive numerical results indicate that the least stable mode is either n = 0 (axisymmetric disturbance) or n = 1 (non-axisymmetric disturbance), which depends on the value of Pr as well as Da. At the least stable mode, the basic flow gets destabilized rapidly in the entire range of Pr for $Da={10}^{-1}$ . There exists a very small range of Pr in the neighborhood of Pr = 0.3 in which the destabilizing characteristics of Pr changes into stabilizing characteristic for $Da={10}^{-2},\hspace{0.17em}{10}^{-3}$ , and ${10}^{-4}$ owing to the change of instability mechanism from thermal-shear to thermal-buoyant. The basic flow stabilizes on reducing the media permeability by varying Da from ${10}^{-1}$ to ${10}^{-4}$ for the considered values of Pr. The magnitudes of disturbance radial and circumferential velocities are found to be less than the disturbance axial velocity due to the forced flow in the axial direction. The multi-cellular structure of circumferential and axial velocities is converted into bi-cellular for a relatively large value of Pr.

In this study we have obtained a new exact model for relativistic stellar object by solving Einstein’s field equation with help of Buchdahl metric. The model is capable to represent some known compact stars like Her X-1,4U 1538-52 and SAX J1808.4-3658. The model satisfies the regularity, casuality, stability and energy conditions. Using the Tolman–Oppenheimer–Volkoff equations, we explore the hydrostatic equilibrium for an uncharged case. We have also compared these conditions with graphical representations that provide strong evidences for more realistic and viable models.

This paper discusses an alternative study approach with multiple lessons learned from a recent successful infill drilling campaign in a medium-sized brownfield. The team conducted a practical and an optimized subsurface study, including the no-frills classical reservoir engineering and a simple sector model to justify the infill wells. From idea generation to monetization of the barrels, it was fast and cost effective without compromising technical assurance. Results of the infill drilling campaign and lessons learned are discussed in this paper. This is a case study on how a comprehensive understanding of reservoir complexity using creative data integration can be an adequate tool for field development. The results of the campaign demonstrated that an optimized study helps the operator and partners make an efficient investment decision in materializing development opportunities.