The mathematical modeling of a gas network is a powerful tool in order to identify the behavior of system under the different conditions. The modeling can be performed both for the steady state and unsteady state conditions. It is possible to use the fluid flow basic governing equations or the electrical analogy concept for developing the model. The second approach provides a simpler and more r...

The present study deals with the analysis of unsteady boundary layer flow and heat transfer of an incompressible micropolar fluid over a stretching sheet when the sheet is stretched in its own plane. The velocity and temperature are assumed to vary linearly with the distance along the sheet. Two equal and opposite forces are impulsively applied along the x-axis so that the sheet is stretched, k...

Unsteady boundary layer flow of an incompressible micropolar fluid over a stretching sheet when the sheet is stretched in its own plane is studied in this paper. The stretching velocity is assumed to vary linearly with the distance along the sheet. Two equal and opposite forces are impulsively applied along the x-axis so that the sheet is stretched, keeping the origin fixed in a micropolar flui...

This paper analyses the unsteady, two-dimensional stagnation point flow of an incompressible viscous fluid over a flat sheet when the flow is started impulsively from rest and at the same time, the sheet is suddenly stretched in its own plane with a velocity proportional to the distance from the stagnation point. The partial differential equations governing the laminar boundary layer forced con...

1. Introduction A great variety of flows with importance to practical engineering applications are inherently unsteady and virtually all of the Newtonian fluid flows in nature are turbulent. Therefore, it is natural and unavoidable to deal with unsteady turbulent flows when Computational Fluid Dynamics (CFD) techniques are applied to engineering design and industrial use. CFD for general fluid ...

In this study, a two-step principal component analysis (TS-PCA) is proposed to handle the dynamic characteristics of chemical industrial processes in both steady state and unsteady state. Differently from the traditional dynamic PCA (DPCA) dealing with the static cross-correlation structure and dynamic auto-correlation structure in process data simultaneously, TS-PCA handles them in two steps: ...

In this work, an unsteady state analysis of the compression cycle of a small hermetic reciprocating compressor for domestic refrigeration was carried out. The mass and energy balances were applied to the refrigerant inside the cylinder in order to determine the mass and temperature behaviour through the compression process. A specific onedimensional model of the valves was developed to calculat...