1D:Dialog InfoLastCalculationRun - Versionsgeschichte

Barbara: /* "Status of Calculation": */

2009-03-27T08:32:12Z

"Status of Calculation":

← Nächstältere Version		Version vom 27. März 2009, 10:32 Uhr
Zeile 73:		Zeile 73:
	</TD>		</TD>
	</TR>		</TR>
	</TABLE>		</TABLE><TABLE>

	<TABLE>
	<TR><TD>positive</TD>		<TR><TD>positive</TD>
	<TD>:</TD>		<TD>:</TD>
	<TD>indoor direction ~~[##update##]~~ (positive X-direction),</TD>		<TD>indoor direction (positive X-direction),</TD>
	</TR>		</TR>
	<TR><TD>negative</TD>		<TR><TD>negative</TD>
	<TD>:</TD>		<TD>:</TD>
	<TD>outdoor direction ~~[##update##]~~ (negative X-direction).</TD>		<TD>outdoor direction (negative X-direction).</TD>
	</TR>		</TR>
	</TABLE>		</TABLE>


	<P>		<P>
	These moisture flows serve to calculate the moisture balance (see below).		These moisture flows serve to calculate the moisture balance (see below).

Len: /* "Status of Calculation": */

2008-09-16T17:53:16Z

"Status of Calculation":

Len am 16. September 2008 um 17:50 Uhr

2008-09-16T17:50:59Z

Änderungen zeigen

Len: Die Seite wurde neu angelegt: = Dialog: Status of Last Calculation = Bild:DialogStatusOfLastCalculation_03.gif
This dialog displays a short summary of the calculation results.
=== &qu...

2008-09-16T17:39:22Z

Die Seite wurde neu angelegt: = Dialog: Status of Last Calculation = Bild:DialogStatusOfLastCalculation_03.gif This dialog displays a short summary of the calculation results. === &qu...

Neue Seite

= Dialog: Status of Last Calculation =

[[Bild:DialogStatusOfLastCalculation_03.gif]]

This dialog displays a short summary of the calculation results.


=== "Water Content" (1): ===


For each layer WUFI displays the initial water content, the final water content, and
the minimum and maximum water contents that occurred during the calculation. 
This allows you a quick first assessment of what happened to the component during the
simulation (e.g., it dried out or accumulated water etc). 
  


<H3>"Status of Calculation":</H3>

<TABLE>
<TR><TD WIDTH="10"> </TD>
<TD>"Simulation: Time and Date" (2):
</TD>
</TR>
<TR><TD> </TD>
<TD>The time and date when the simulation was performed. 
  
</TD>
</TR>

<TR><TD> </TD>
<TD>"Computing Time" (2):
</TD>
</TR>
<TR><TD> </TD>
<TD>The time it took WUFI to perform the calculation. 
  
</TD>
</TR>

<TR><TD> </TD>
<TD>"No. of Convergence Failures" (3):
</TD>
</TR>
<TR><TD> </TD>
<TD>
WUFI uses an iterative method for the solution of the transport equations.
Sometimes, the convergence is very slow and WUFI reaches the maximum allowed
number of iterations without the interim solutions meeting the termination
criteria.


In this case, the iteration is stopped and the convergence achieved so far
compared to somewhat relaxed criteria. If these are met, WUFI accepts the
results and continues with the next time step. If the criteria are not met, WUFI
also accepts the result and continues with the calculation, but the number
of convergence failures is increased by one.


The total number of convergence failures is a first hint concerning the
reliability of the results. The fact that a convergence failure has been
registered does not tell, however, how large the remaining error was when
the iteration was stopped.


It is quite possible that the termination criteria were missed by a small
margin only and the convergence failure is therefore irrelevant; this is
usually the case.


Sometimes it is also possible, however, that a numerical instability has
developed and the iteration steps drift farther and farther away from the
real solution. Then the solution left by the aborted iterations is only a bad
(in rare cases very bad) approximation for the solution of the transport
equations. This often reveals itself by water appearing or disappearing in
the middle of the component, without the boundary conditions having called
for such behaviour. The results are sudden jumps in the course of the water
content and a bad water balance (see below).


The criteria for a convergence failure have been adjusted to be very sensitive.
Experience shows that in general a few convergence failures are harmless. If
you have calculated over one year, one or two convergence failures are in
general nothing to worry about. 
Numerical instabilities, however, usually announce their arrival by a
generally higher number of convergence failures. Fifty convergence failures
per year are possibly (but not always) indicating a problem.


A better indicator for the quality of the results is the water balance
(see below). 
  

</TD>
</TR>

<TR><TD> </TD>
<TD>"No. of Rain Absorption Failures" (3):
</TD>
</TR>
<TR><TD> </TD>
<TD>
WUFI uses an iterative method to determine the amount of water absorbed when
rain hits the component surface, because there may be less rain than the
component can theoretically absorb during the time step. This limitation imposed
by the amount of rain has to be allowed for, but the amount actually absorbed
can only be determined iteratively; see the relevant question in the
[[FASQ:QuestionsAndAnswers | Questions & Answers]] section).


It is possible although very rare that convergence is too slow and WUFI
reaches the maximum allowed number of iterations without the interim
solutions meeting the termination criteria.


In this case, the iteration is stopped, WUFI accepts the results and continues
with the next time step, but the number of rain absorption failures is
increased by one.


This is usually no reason to worry, since a rain absorption failure normally
doesn't mean the result of the time step is terribly wrong, it only means that
the termination criteria - which are somewhat arbitrary anyway - haven't been
met. The result of the time step is usually well acceptable in view of all
the simplifications and approximations that go into such a simulation model
in the context of building physics. 
  

</TD>
</TR>

<TR><TD> </TD>
<TD>"Fluxes e (ke, de)",, 
"Fluxes i (ki, di)" (4):
</TD>
</TR><TD> </TD>
<TD>
the total amount of water which flows into or out of the component during
the calculation.

<TABLE>
<TR><TD>ke</TD>
<TD>:</TD>
<TD>by capillary transport at the exterior surface,</TD>
</TR>
<TR><TD>de</TD>
<TD>:</TD>
<TD>by vapour transport at the exterior surface,</TD>
</TR>
<TR><TD>ki</TD>
<TD>:</TD>
<TD>by capillary transport at the interior surface,</TD>
</TR>
<TR><TD VALIGN="TOP">di</TD>
<TD VALIGN="TOP">:</TD>
<TD>by vapour transport at the interior surface.(*) 
  
</TD>
</TR>
</TABLE>

<TABLE>
<TR><TD>positive</TD>
<TD>:</TD>
<TD>indoor direction [##update##] (positive X-direction),</TD>
</TR>
<TR><TD>negative</TD>
<TD>:</TD>
<TD>outdoor direction [##update##] (negative X-direction).</TD>
</TR>
</TABLE>

These moisture flows serve to calculate the moisture balance (see below).


Please note: These are not the moisture flows through the surface,
but the flows between the surface and the component. It may happen that
water condenses at a cold surface in such amounts that the absorption capacity
of the building material is surpassed and the water runs off at the surface.
This run-off 'disappears' for the calculation, so that the amount of water
arriving at the surface from the environment may not be identical to the
amount entering into the component from the surface.


Therefore the above moisture flows are not evaluated at the surfaces but at
the boundaries between the first and the second, and between the next-to-last
and the last grid element. This has to be borne in mind if the above numbers
are to be interpreted, especially if the first or last element has some
appreciable thickness. 
  



(*) It is also the reason why the above definition just vaguely says
"at the surface" instead of "through the surface".


So do not wonder, for instance, if you get a non-zero capillary flow ki at
the interior surface, although it certainly never rains there. This is a
capillary flow closely (half an element) below the surface. 
  

</TD>
</TR>

<TR><TD> </TD>
<TD>"Balance 1 [kg/m²]", 
"Balance 2 [kg/m²]" (4):
</TD>
</TR>
<TR><TD> </TD>
<TD>
the change in 'total water content' during the calculation, and the sum
of the 'surface flows' (ka+da-ki-di, see above).


Ideally, these two numbers should be identical, since any change in the total
water content must result from moisture being transported through the surfaces.
Rounding errors and convergence problems may cause discrepancies,
however. 
If the discrepancies become too large, you should repeat the calculation
with appropriate modifications (see below).


Please note: for the reasons discussed above, the first and the last grid
element are not allowed for in the determination of this 'total water content'
so that it is less than the total water content you get as the official result
of the calculation. Therefore, the change in the 'total water content' may also
slightly differ from what you infer from the official results, especially if
the first or last element has some appreciable thickness.


These numbers are only meant to provide a consistency check on the numerical
calculation. Analyses of the water content and the surface flows should be done
using the calculation results themselves only. 
  



If you get too many convergence failures or a bad water balance, you should
check whether your choice of the numerical grid is indeed appropriate for the
project at hand. A typical problem, for instance, are condensation phenomena
at a layer boundary or at a surface, so that steep water content gradients occur
which can not be represented adequately if the grid is too coarse at that
location. You may need to use the fine grid option or to
[[1D:Dialog_Assembly | adapt the grid manually]].


This is further discussed in
[[Discussion:WUFI-Pro_PerformanceandLimitations | "WUFI's Performance and
Limitations"]], in
[[1D:Dialog_Assembly | "Dialog: Assembly / Monitor Positions"]],
in [[1D:Dialog_Numerics | "Dialog: Numerics"]] and in the
[[FAQ:QuestionsAndAnswers | Questions & Answers section]]. 
  

</TD>
</TR>
</TABLE>

=== "Calculation locked" (5): ===

If after a calculation you inadvertently restart it, the existing results are
overwritten and lost. There is a security query, but if you want to avoid any risk,
lock the calculation and save the project file once more (to make the lock permanent).


This is especially advisable if the results of long and tedious calculations shall be
demonstrated in a hectic atmosphere...

← Nächstältere Version		Version vom 16. September 2008, 19:53 Uhr
Zeile 19:		Zeile 19:
	=== "Status of Calculation": ===		=== "Status of Calculation": ===

	<B>"Simulation: Time and Date"</B> <FONT COLOR="#FF0000"><B>(2)</B></FONT>:		<B>"Simulation: Time and Date"</B> <FONT COLOR="#FF0000"><B>(2)</B></FONT>:<BR>
	The time and date when the simulation was performed.<BR>		The time and date when the simulation was performed.<BR>
	<BR>		<BR>
	<B>"Computing Time"</B> <FONT COLOR="#FF0000"><B>(2)</B></FONT>:		<B>"Computing Time"</B> <FONT COLOR="#FF0000"><B>(2)</B></FONT>:<BR>
	The time it took WUFI to perform the calculation.<BR>		The time it took WUFI to perform the calculation.<BR>
	<BR>		<BR>
	<B>"No. of Convergence Failures"</B> <FONT COLOR="#FF0000"><B>(3)</B></FONT>:		<B>"No. of Convergence Failures"</B> <FONT COLOR="#FF0000"><B>(3)</B></FONT>:<BR>
	WUFI uses an iterative method for the solution of the transport equations. Sometimes, the convergence is very slow and WUFI reaches the maximum allowed number of iterations without the interim solutions meeting the termination criteria.<BR>		WUFI uses an iterative method for the solution of the transport equations. Sometimes, the convergence is very slow and WUFI reaches the maximum allowed number of iterations without the interim solutions meeting the termination criteria.<BR>
	<BR>		<BR>
Zeile 41:		Zeile 41:
	A better indicator for the quality of the results is the water balance (see below).<BR>		A better indicator for the quality of the results is the water balance (see below).<BR>
	<BR>		<BR>
	<B>"No. of Rain Absorption Failures"</B> <FONT COLOR="#FF0000"><B>(3)</B></FONT>:		<B>"No. of Rain Absorption Failures"</B> <FONT COLOR="#FF0000"><B>(3)</B></FONT>:<BR>
	WUFI uses an iterative method to determine the amount of water absorbed when rain hits the component surface, because there may be less rain than the component can theoretically absorb during the time step. This limitation imposed by the amount of rain has to be allowed for, but the amount actually absorbed can only be determined iteratively; see the relevant question in the [[FAQ:QuestionsAndAnswers \| Questions & Answers]] section).<BR>		WUFI uses an iterative method to determine the amount of water absorbed when rain hits the component surface, because there may be less rain than the component can theoretically absorb during the time step. This limitation imposed by the amount of rain has to be allowed for, but the amount actually absorbed can only be determined iteratively; see the relevant question in the [[FAQ:QuestionsAndAnswers \| Questions & Answers]] section).<BR>
	<BR>		<BR>
Zeile 51:		Zeile 51:
	<BR>		<BR>
	<B>"Fluxes e (ke, de)",</B>,<BR>		<B>"Fluxes e (ke, de)",</B>,<BR>
	<B>"Fluxes i (ki, di)"</B> <FONT COLOR="#FF0000"><B>(4)</B></FONT>:		<B>"Fluxes i (ki, di)"</B> <FONT COLOR="#FF0000"><B>(4)</B></FONT>:<BR>
	the total amount of water which flows into or out of the component during the calculation.		the total amount of water which flows into or out of the component during the calculation.

Zeile 117:		Zeile 117:
	</P>		</P>
	<B>"Balance 1 [kg/m²]",</B><BR>		<B>"Balance 1 [kg/m²]",</B><BR>
	<B>"Balance 2 [kg/m²]"</B> <FONT COLOR="#FF0000"><B>(4)</B></FONT>:		<B>"Balance 2 [kg/m²]"</B> <FONT COLOR="#FF0000"><B>(4)</B></FONT>:<BR>
	the change in 'total water content' during the calculation, and the sum of the 'surface flows' (ka+da-ki-di, see above).<BR>		the change in 'total water content' during the calculation, and the sum of the 'surface flows' (ka+da-ki-di, see above).<BR>
	<BR>		<BR>

1D:Dialog InfoLastCalculationRun - Versionsgeschichte

Barbara: /* "Status of Calculation": */

Len: /* "Status of Calculation": */

Len am 16. September 2008 um 17:50 Uhr

Len: Die Seite wurde neu angelegt: = Dialog: Status of Last Calculation = Bild:DialogStatusOfLastCalculation_03.gif This dialog displays a short summary of the calculation results. === &qu...

Len: Die Seite wurde neu angelegt: = Dialog: Status of Last Calculation = Bild:DialogStatusOfLastCalculation_03.gif
This dialog displays a short summary of the calculation results.
=== &qu...