Control Volume Analysis—Mass and Energy Conservation

2011 ◽  
pp. 427-460
Keyword(s):  
Energy Conservation ◽  
Control Volume ◽  
Volume Analysis ◽  
Mass And Energy Conservation

On symmetric intrusions in a linearly stratified ambient: a revisit of Benjamin's steady-state propagation results

2021 ◽  
Vol 929 ◽  
Author(s):  
M. Ungarish
Keyword(s):  
Steady State ◽  
Control Volume ◽  
Gravity Current ◽  
Head Loss ◽  
Stability Criteria ◽  
Ambient Fluid ◽  
Height Ratio ◽  
Stagnation Line ◽  
Volume Analysis ◽  
State Propagation

Previous studies have extended Benjamin's theory for an inertial steady-state gravity current of density $\rho _{c}$ in a homogeneous ambient fluid of density $\rho _{o} < \rho _{c}$ to the counterpart propagation in a linearly stratified (Boussinesq) ambient (density decreases from $\rho _b$ to $\rho _{o}$ ). The extension is typified by the parameter $S = (\rho _{b}-\rho _{o})/(\rho _{c}-\rho _{o}) \in (0,1]$ , uses Long's solution for the flow over a topography to model the flow of the ambient over the gravity current, and reduces well to the classical theory for small and moderate values of $S$ . However, for $S=1$ , i.e. $\rho _b = \rho _c$ , which corresponds to a symmetric intrusion, various idiosyncrasies appear. Here attention is focused on this case. The control-volume analysis (balance of volume, mass, momentum and vorticity) produces a fairly compact analytical formulation, pending a closure for the head loss, and subject to stability criteria (no inverse stratification downstream). However, we show that plausible closures that work well for the non-stratified current (like zero head loss on the stagnation line, or zero vorticity diffusion) do not produce satisfactory results for the intrusion (except for some small ranges of the height ratio of current to channel, $a = h/H$ ). The reasons and insights are discussed. Accurate data needed for comparison with the theoretical model are scarce, and a message of this paper is that dedicated experiments and simulations are needed for the clarification and improvement of the theory.

Injection Pump Analysis

2012 ◽  
Author(s):  
William W. Schultz ◽  
Eric Johnsen ◽  
Bosuk Han ◽  
Sung Park
Keyword(s):  
Control Volume ◽  
Optimal Performance ◽  
Device Performance ◽  
Volume Analysis ◽  
Injection Pump ◽  
Simple Geometry ◽  
Simplified Analysis ◽  
Moving Parts

An injection pump is one of the simplest mechanics devices imaginable with no moving parts and a very simple geometry. We examine the device performance for steam injectors using primarily a control volume analysis and consider to what extent this simplified analysis represents optimal performance. We seek the rationale for performing CFD studies and develop optimization scenarios.

scholarly journals Lift force for cylindrical and elliptical Coandă aircraft design

2018 ◽  
Vol 7 (4.13) ◽  
pp. 137
Author(s):  
Mohd Faisal Abdul Hamid ◽  
Azmin Shakrine Mohd Rafie ◽  
Ezanee Gires ◽  
Abd. Rahim Abu Talib
Keyword(s):  
Lift Force ◽  
Control Volume ◽  
Aircraft Design ◽  
The Body ◽  
Viscous Effect ◽  
Extended Version ◽  
Volume Analysis ◽  
Flow Effects ◽  
And Performance ◽  
Rotary Wing

Small aerial vehicles possess advantages in terms of size and accessibility in performing a variety of tasks. Presently, their design and performance is dependent on variations of conventional aerodynamic configurations (fixed- and rotary-wing). A disadvantage for these configurations is the aerodynamic potential between the mainstream airflow and the body surfaces are not fully utilized. To solve this issue, the Coandă effect is proposed whereby a high-velocity jet is blown tangentially over a curved surface to increase circulation and lift. Prior to the costly approach (experimental and numerical), an analytical formulation (via control volume analysis) to predict the aerodynamic Coandă lift force of the design concept is developed. This is an extended version of the existing mathematical formulations, capturing viscous flow effects. It is also pertinent for circular and elliptical-shaped designs. The results obtained show that the total lift force is dependent on the jet velocity, outflow angle, dimensions of the jet slot, the projected surface area, and the viscous effect. The approach has demonstrated how this modelling technique is effective in calculating the lift force for cylindrical and elliptical Coandă aircraft design.   

Aerodynamic Throttling of Two-Dimensional Nozzle Flows

1972 ◽  
Vol 23 (1) ◽  
pp. 53-61 ◽  
Author(s):  
R H Nunn ◽  
H Brandt
Keyword(s):  
Control Volume ◽  
Interaction Region ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Volume Analysis ◽  
Throat Region ◽  
Mainstream Flow ◽  
Nozzle Flows

SummaryThe inviscid interaction resulting from the penetration of a jet of air into the throat region of a bounded mainstream flow is investigated analytically and experimentally. Taking into account the effects of jet shocks, a control volume analysis is used to calculate the mainstream and jet conditions at the boundaries of the interaction region. These results are then used to estimate the shape of the interface separating the jet and mainstream. Particular attention is given to the throttling of the mainstream flow and the analytical predictions show agreement with the experimental measurements.

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