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Slow iteration proces in DF5
21-07-2020, 10:14 AM,
#1
Slow iteration proces in DF5
Affected version: Ple4Win Professional v4.6.1

Hello,

There is a slow iteration process going on in DF5. I know, you can change the stability parameters and decrease the numbers of iteration steps from 150 to 50.
Between the 2 steps the time needed for the iteration is taking too long. Compare the delta timing between Ple4Win Professional 4.6.0 and Ple4Win Professional v4.6.1.

For example in BC3 with no temparature and with no pressure in the calculation it takes too long to do a calculation (with almost no axial displacements). I know the boundary conditions can influence and also if there are supports and joints.

But compare an old calculation (prior to Ple4Win Professional v4.6.1) and compare the lastchanges column in the table time it took (between an unlock and locked table, for example: ITMON).
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21-07-2020, 10:45 AM,
#2
RE: Slow iteration proces in DF5
Thanks for mentioning this. There have been no great changes to the iteration mechanics between version 4.6.0 and 4.6.1, so I am a bit surprised to hear that you experience a much slower iteration process in the latter version.

Have you checked that both versions use the same options? In particular, the iteration process is slower if pipe ovalisations redistribution is switched on in DF5. Please make sure that in both cases it is either switched both on or both off.

We haven't noticed a significant speed difference between the two versions here. If you have an example to the contrary please send us the project files, we will then look into it.
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21-07-2020, 01:12 PM,
#3
RE: Slow iteration proces in DF5
Hello Jens,

Herebelow there is a screenshot how long a displacement calculation took (in this example almost 45 minutes).
   

In this case I used this situation:

   

I will send the project file by email to info@eds-ple.nl.

Suggestion: If there are support try to split systems in parts which has low displacements sections and not to put it as continuum convergence iteration equation, I think.
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21-07-2020, 01:56 PM, (This post was last modified: 21-07-2020, 06:40 PM by shaswin.)
#4
RE: Slow iteration proces in DF5
In another project file without temperature and without pressure (BC 3). The iteration process time takes almost the same to do the displacement calculations.

Try to look at these values:

   


Those are very low values. Is this normal for convergence? It seems it doesn't always give the near stability message in the messages box. It should exit afte a few (maybe 3x times) near stability messages.

A solution for this problem is to put a value textbox in the Ple4Win Options, where this dispadd. accuracy can be changed by an PLE-user. Give for the PLE-user in this textbox a standard default value for a default pipeline system.
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31-07-2020, 05:35 PM,
#5
RE: Slow iteration proces in DF5
If you move the tablesup reference from TFSPRS table to ELSPRS table (verticale springs only) the iteration process will run better and faster.
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03-08-2020, 02:14 PM,
#6
RE: Slow iteration proces in DF5
I haven't had time to look into your case yet, I will do so as soon as possible.

Your last post may contain the reason for the slow iteration process (I have to check to be sure): If you change from table support to elastic support, the pipe is suddenly also constraint in the upward direction. With table supports it is not, so most likely you get a kind of rattling during iterations: With one iteration the pipe touches the support, with the next it floats free above it, and then it touches again and so on. This kind of constantly changing environment makes iterating towards a solution very slow.
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