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CFD

2010-09-08T21:19:35Z

Reverted edits by Fgsdfsdfc (Talk) to last version by Peter

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	The CFD acronym has also recently become popular in economics, where it stands for something completely different called [http://en.wikipedia.org/wiki/Contract_for_difference contract for difference].		The CFD acronym has also recently become popular in economics, where it stands for something completely different called [http://en.wikipedia.org/wiki/Contract_for_difference contract for difference].
-	~~[http://www.bestessays.ca custom essay writing service]~~	+
	[[Category: Acronyms]]		[[Category: Acronyms]]

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2010-09-08T21:19:25Z

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2010-09-08T16:12:01Z

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2010-09-08T15:52:35Z

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CFD

2010-09-07T12:20:26Z

←Older revision		Revision as of 12:20, 7 September 2010
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	The CFD acronym has also recently become popular in economics, where it stands for something completely different called [http://en.wikipedia.org/wiki/Contract_for_difference contract for difference].		The CFD acronym has also recently become popular in economics, where it stands for something completely different called [http://en.wikipedia.org/wiki/Contract_for_difference contract for difference].
-		+	[http://www.bestessays.ca custom essay writing service]
	[[Category: Acronyms]]		[[Category: Acronyms]]

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2010-09-07T12:19:37Z

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2010-09-03T16:31:26Z

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2010-09-03T10:01:05Z

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Introduction to turbulence/Free turbulent shear flows

2010-09-02T11:04:13Z

Order of magnitude estimates:

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	But this is exactly what we would have gotten by taking <math> U_{s} = U_{cl} </math> as we agreed above. We simply have absorbed any differences into our choice of <math> L </math>. When considering specific problems and applying similarity techniques, the seemingly arbitrary choices here become quite precise constraints (as we shall see).		But this is exactly what we would have gotten by taking <math> U_{s} = U_{cl} </math> as we agreed above. We simply have absorbed any differences into our choice of <math> L </math>. When considering specific problems and applying similarity techniques, the seemingly arbitrary choices here become quite precise constraints (as we shall see).
		+
		+	We still haven't talked about how to estimate the velocity scale for <math> V </math>, the cross-stream mean velocity component. From the continuity equation we know that:
		+
		+	<table width="70%"><tr><td>
		+	:<math>
		+	\frac{\partial V}{\partial y} = - \frac{\partial U}{\partial x}
		+	</math>
		+	</td><td width="5%">(9)</td></tr></table>
		+
		+	From our considerations above, we know that:
		+
		+	<table width="70%"><tr><td>
		+	:<math>
		+	\frac{\partial U}{\partial x} \sim \frac{\Delta U_{s}}{L}
		+	</math>
		+	</td><td width="5%">(10)</td></tr></table>
		+
		+	If there is no mean cross flow in the external stream, then the scale for
		+	<math> V </math> is the same as the scale for changes in <math> V </math>. Therefore,
		+
		+	<table width="70%"><tr><td>
		+	:<math>
		+	\frac{\partial V}{\partial y} \sim \frac{V_{s}}{\delta}
		+	</math>
		+	</td><td width="5%">(11)</td></tr></table>
		+
		+	It follows immediately that the order of magnitude of the cross-stream velocity is:
		+
		+	<table width="70%"><tr><td>
		+	:<math>
		+	V_{s} \sim \Delta U_{s} \frac{\delta}{L}
		+	</math>
		+	</td><td width="5%">(12)</td></tr></table>
		+
		+	We might have expected something like this if we had thought about it. If the <math> V </math>-velocity were of the same order as the <math> U </math> - velocity, how could the flow in any sense be a "thin shear flow". On the other hand, it also makes sense that

CFD-Wiki:Donated texts

2010-09-01T22:15:52Z

←Older revision		Revision as of 22:15, 1 September 2010
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	:Date written: June 2007		:Date written: June 2007
	:Date donated: July 2007		:Date donated: July 2007
-	:Summary: Rui Igreja's master thesis at the University of Aveiro, Portugal.<br> Commonly used methods for injection moulding simulation involve a considerable number of simplifications, leading to a significant reduction of the computational effort but, in some cases also to limitations. In this work, Reaction Injection Moulding (RIM) simulations are performed with a minimum of simplifications, by using the general purpose CFD software package CFX, designed for numerical simulation of fluid flow and heat and mass transfer.<br>The CFX’s homogeneous multiphase flow model, which is generally considered to be the appropriate choice for modelling free surface flows where the phases are completely stratified and the interface is well defined, is shown to be unable to model the filling process correctly. This problem is overcome through the implementation of the inhomogeneous model in combination with the free-slip boundary condition for the air phase.<br>The cure reaction is implemented in the code as a transport equation for an additional scalar variable, with a source term. Various transient and advection schemes are tested to determine which ones produce the most accurate results.<br>Finally, the mass conservation, momentum, cure and energy equations are implemented all together to simulate the simultaneous filling and curing processes present in the RIM process. The obtained numerical results show a good global accuracy when compared with other available numerical and experimental results, though considerably long computation times are required to perform the simulations.<br>(<i>A better quality version (6.~~3 MB~~) is available ~~here~~:</i> http://~~ruiigreja~~.~~googlepages~~.com/~~RuiIgreja_MasterThesis.pdf~~)	+	:Summary: Rui Igreja's master thesis at the University of Aveiro, Portugal.<br> Commonly used methods for injection moulding simulation involve a considerable number of simplifications, leading to a significant reduction of the computational effort but, in some cases also to limitations. In this work, Reaction Injection Moulding (RIM) simulations are performed with a minimum of simplifications, by using the general purpose CFD software package CFX, designed for numerical simulation of fluid flow and heat and mass transfer.<br>The CFX’s homogeneous multiphase flow model, which is generally considered to be the appropriate choice for modelling free surface flows where the phases are completely stratified and the interface is well defined, is shown to be unable to model the filling process correctly. This problem is overcome through the implementation of the inhomogeneous model in combination with the free-slip boundary condition for the air phase.<br>The cure reaction is implemented in the code as a transport equation for an additional scalar variable, with a source term. Various transient and advection schemes are tested to determine which ones produce the most accurate results.<br>Finally, the mass conservation, momentum, cure and energy equations are implemented all together to simulate the simultaneous filling and curing processes present in the RIM process. The obtained numerical results show a good global accuracy when compared with other available numerical and experimental results, though considerably long computation times are required to perform the simulations.<br>( <i>A better quality version (6.1MB .pdf) is available from:</i><b> http://sites.google.com/site/ruiigreja2/MyMasterThesis</b> )

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2010-09-01T17:12:16Z

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2010-09-01T05:52:43Z

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