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Pressure-Volume loops showing end-systolic pressure volume relationship. End-systolic pressure volume relationship (ESPVR) describes the maximal pressure that can be developed by the ventricle at any given LV volume. This implies that the PV loop cannot cross over the line defining ESPVR for any given contractile state.
The minimum and maximum volumes (V max and V min) from each loop in the series of loops are plotted on a graph. V max and V min lines are extrapolated and at their point of intersection, where V max is equal to V min, must be zero—conductance is parallel conductance only. The volume at this point is the correction volume.
Very useful information can be derived by examination and analysis of individual loops or series of loops, for example: the horizontal distance between the top-left corner and the bottom-right corner of each loop is the stroke volume [5] the line joining the top-left corner of several loops is the contractile or inotropic state. [6]
Flow-Volume loop showing successful FVC maneuver. Positive values represent expiration, negative values represent inspiration. At the start of the test both flow and volume are equal to zero (representing the volume in the spirometer rather than the lung). The trace moves clockwise for expiration followed by inspiration.
The lumped parameter model consists in a system of ordinary differential equations that adhere to the principles of conservation of mass and momentum balance. The model is obtained exploiting the electrical analogy where the current represents the blood flow, the voltage represents the pressure difference, the electric resistance plays the role of the vascular resistance (determined by the ...
Since then it has been extensively used by many researchers to solve different kinds of fluid flow and heat transfer problems. [1] Many popular books on computational fluid dynamics discuss the SIMPLE algorithm in detail. [2] [3] A modified variant is the SIMPLER algorithm (SIMPLE Revised), that was introduced by Patankar in 1979. [4]
The Newton loop-node method is based on Kirchhoff’s first and second laws. The Newton loop-node method is the combination of the Newton nodal and loop methods and does not solve loop equations explicitly. The loop equations are transformed to an equivalent set of nodal equations, which are then solved to yield the nodal pressures.
It is a scalar function, defined as the integral of a fluid's characteristic function in the control volume, namely the volume of a computational grid cell. The volume fraction of each fluid is tracked through every cell in the computational grid, while all fluids share a single set of momentum equations, i.e. one for each spatial direction.