some beginner WEST questions

Hello,
I'm a beginner user of WEST and I have some basic questions about its operation that I couldn't solve with the tutorials and guide information:

1) Is it possible to change the selected biological model (Instance) once I've created the ptoject? How?

2) I've noticed that when you launch a DYN simulation it starts from the final values of the previous SS simulation. How can I do to start from the last DYN results? Is it possible to repeat cyclically the influent pattern (without copying and pasteing it several times in the .txt input file)?

3) It seems to me that you can load your input data from a .xls or .txt file but I have some problems in order to recognise the correct units when I use a .xls files (especially the time column). How can avoid that? or should I use always .txt files?

4) I haven't found any option for the phosphorus precipitation in the Chemical Dosing section of the Block Library. Is there any option to incorporate this phenomenon in the simulation? what moldel should I use?

5) Is it possible to see the mathematical equation of each model and how are they implemented in west?

I would appraciate any information that help me with that issues.
Thank you

> 1) Is it possible to change the selected biological model (Instance) once I've created the ptoject? How?

Yes, this can be done through the "Block Library Setup" dialog, which is in the "Project" menu (as of WEST 2014).

> 2) I've noticed that when you launch a DYN simulation it starts from the final values of the previous SS simulation.

The behavior can be altered by switching off the flag labeled "Automatically copy the current state of the Steady State simulation to the Dynamic simulation", and manipulating the "Initialize Simulation" options in the "Project" menu.

> Is it possible to repeat cyclically the influent pattern (without copying and pasteing it several times in the .txt input file)?

The WEST engine actually supports this, but this functionality is not available through the GUI.

> 3) It seems to me that you can load your input data from a .xls or .txt file but I have some problems in order to recognise the correct units when I use a .xls files (especially the time column). How can avoid that? or should I use always .txt files?

You should be able to use either TXT or XLS(X). In the case of TXT 2 header styles are supported, i.e. the old style with "%%Version3.3...", and the newer style with "#". In the case of XLS(X) only the latter is supported.

> 5) Is it possible to see the mathematical equation of each model and how are they implemented in west?

The Model Editor (only available with WESTforOPTIMIZATION) is the tool to use to explore and modify the model library's structure and equations.

Hello,
here I have some new questions about the WEST performance. I would be very pleased if anyone could help me.

1. Does WEST calculate by itself basic system operational paràmeters values like SRT or OLR? What can I do to see them? So far I've only achieved it by creating them as new algebraic variables and introducing their formula.

2. I have some problems to connect some input and output blocks to the flow diagram (please find the attached file):
  error 1) I've been trying to define a temperature cycle through an input block connected to the ASU unit but when I execute the simulation it's not reproduced.
  error 2) It’s not possible to connect an output bock for a variable to be shown (OD for instance) from the ASU block.
  error 3) It’s not possible to connect an Iron dosing or Alum dosing block to a flow line (same error message as in error 2).
How should I proceed to do that properly?

3) Is it possible to use an anaerobic digester in all the models (instances)? How can I see how WEST does the conversion of ASM1 or ASM2d variables into ADM1 variables?

4) I haven't seen any specific block for the aerobic digesters. Are we supposed to model it like a norma ASU unit?

Thank you very much

[quote author=Ruben link=topic=20133.msg26060#msg26060 date=1496387250]
1. Does WEST calculate by itself basic system operational paràmeters values like SRT or OLR? What can I do to see them? So far I've only achieved it by creating them as new algebraic variables and introducing their formula.
[/quote]
No, not 'automatically'.
Yes, one way is to create so-called [b]Calculator Variables[/b], which is what you did. This approach has advantages (it's very quick) and disadvantages (not reusable outside of the project).
Another way (as of rel.2017) is to create a [b]Top-level State Variable[/b] - with the advantage, over the Calculator Variable, that you can write complex expressions.

For SRT though, you should rather use the 'OperationalParameters' model associated with the [b]Process Calculator block[/b] - and provide the necessary quantities to it by connecting the relevant terminals in your layout.

[quote author=Ruben link=topic=20133.msg26060#msg26060 date=1496387250]
2. I have some problems to connect some input and output blocks to the flow diagram (please find the attached file):
  error 1) I've been trying to define a temperature cycle through an input block connected to the ASU unit but when I execute the simulation it's not reproduced.
  error 2) It’s not possible to connect an output bock for a variable to be shown (OD for instance) from the ASU block.
  error 3) It’s not possible to connect an Iron dosing or Alum dosing block to a flow line (same error message as in error 2).
How should I proceed to do that properly?
[/quote]
[1] Are you sure you're executing the Dynamic Simulation and not the Steady-State Simulation - which will use the computed average temperature, which may very well be 20 degC?
Or: are you sure the Input block is connected to the Temp variable of the tank - which is the one you're plotting?
[2] The reason why it does not allow you to finalise the connection is because you haven't defined a top-level interface variable of type 'Output'.
Anyway, why do you need an explicit Output block? this is not necessary to e.g. plot a variable, or send it to a file output ...
[3] It should not be the case. Why does your Iron Dosing block not display a valid output terminal? which Instance are you using?


[quote author=Ruben link=topic=20133.msg26060#msg26060 date=1496387250]
3) Is it possible to use an anaerobic digester in all the models (instances)? How can I see how WEST does the conversion of ASM1 or ASM2d variables into ADM1 variables?
[/quote]
No, it can only be used in the scope of an ASM1 Instance.
The Models Guide contains a detailed description of every model.

[quote author=Ruben link=topic=20133.msg26060#msg26060 date=1496387250]
4) I haven't seen any specific block for the aerobic digesters. Are we supposed to model it like a norma ASU unit?
[/quote]
Yes, that would be my approach as well.

For SRT, you may want to have a look at the document "WEST: How to compute SRT and HRT?" in http://userarea.west.mikepoweredbydhi.com/FAQ/

Thank you for your answer. However, in the wake of them I have some other questions:

1. As you recommend me I've tried and achieved to calculate the SRT and HRT variable states by using the Process Calculator Block but it’s not possible for me to calculate the F/M ratio (picture in attached file). What is the reason and how should I proceed? I’ve seen in the description of that block that it should be possible to calculate the F/M ratio. Could it be possible to calculate any other state variable with that block? How can I introduce its formula?

2. I've managed to solve my problems wits the input and output general blocks but I still have problems to introduce an Iron or Alum Dosing block to the diagram. As you told me, my Dosing block doesn't display any valid output terminal but I don't know why. Should I create it previously? How and Where? I'm using the ASM2dM instance.

3. If it's only possible to use the Anaerobic Digestion Blocks when we are using the ASM1 instance, is there any option to evaluate the biological P removal and the anaerobic digester performance in the same simulation?

4. Is there any difference betwen the use of a multiprobe sensor or an especific one to read (and the use) a variable?

Thank you in advance

[quote author=Ruben link=topic=20133.msg26068#msg26068 date=1496508278]
1. As you recommend me I've tried and achieved to calculate the SRT and HRT variable states by using the Process Calculator Block but it’s not possible for me to calculate the F/M ratio (picture in attached file). What is the reason and how should I proceed? I’ve seen in the description of that block that it should be possible to calculate the F/M ratio. Could it be possible to calculate any other state variable with that block? How can I introduce its formula?
[/quote]
The snapshot shows the connection between the calculator block (out) and a data treatment block (in): this has nothing to do with the calculation of the F/M ratio which is an algebraic state variable computed within the calculator block and which needs the relevant input variables.

[quote author=Ruben link=topic=20133.msg26068#msg26068 date=1496508278]
2. I've managed to solve my problems wits the input and output general blocks but I still have problems to introduce an Iron or Alum Dosing block to the diagram. As you told me, my Dosing block doesn't display any valid output terminal but I don't know why. Should I create it previously? How and Where? I'm using the ASM2dM instance.
[/quote]
You're right: those chemical dosing models are not enabled for ASM2dM. It's a mistake: we're going to fix this as soon as possible.

[quote author=Ruben link=topic=20133.msg26068#msg26068 date=1496508278]
3. If it's only possible to use the Anaerobic Digestion Blocks when we are using the ASM1 instance, is there any option to evaluate the biological P removal and the anaerobic digester performance in the same simulation?
[/quote]
Not with the standard library.
In order to achieve that, you need to convert the ASM2 state vector into an ASM1 state vector - which then can be connected to the anaerobic digester block.

[quote author=Ruben link=topic=20133.msg26068#msg26068 date=1496508278]
4. Is there any difference betwen the use of a multiprobe sensor or an especific one to read (and the use) a variable?
[/quote]
No: the multiprobe sensor measures all quantities that are measured by the individual sensors.

Hello again,

thank you for your answers but I've been going going through them and I'm afraid I have some toher doubts:

1 Question: I've been checking the calculator block information and it seems to me that is possible to calculate F/M ratio (attached file question 1). I don't understand what you mean with " this has nothing to do with the calculation of the F/M ratio which is an algebraic state variable computed within the calculator block and which needs the relevant input variables." What should I do to calculate F/M ratio using the calculator block?

2 Question: I 've seen it is not possible to obtain the total volume of the oxidation ditch making the connection between oxidation ditch block and the calculator block (attached image question 2). Could I get the total volume in another way? If it is not possible, then I guess that it's only possible to calculate TRC, HRT AND F/M in this case using algebraic calculator variables. Is it right?

3 Question: I've been exploring the IFAS block and I've noticed there are two flow outputs. What's the difference between Q Under and Q Excess? I haven't found any explanation in the block information. I thought that IFAS reactors used to have obly one outlet and purge was produced in the posterior secondary settler.

Thank you in advance

[quote author=Ruben link=topic=20133.msg26104#msg26104 date=1497435249]
1 Question: I've been checking the calculator block information and it seems to me that is possible to calculate F/M ratio (attached file question 1). I don't understand what you mean with " this has nothing to do with the calculation of the F/M ratio which is an algebraic state variable computed within the calculator block and which needs the relevant input variables." What should I do to calculate F/M ratio using the calculator block?
[/quote]
You need to provide the relevant inputs (data) to the calculator: see Models Guide.
But if you are using the oxidation ditch model, this may not be possible, as this model does not expose all the relevant outputs that are necessary for the calculation - which answers your 2nd question too.

[quote author=Ruben link=topic=20133.msg26104#msg26104 date=1497435249]
3 Question: I've been exploring the IFAS block and I've noticed there are two flow outputs. What's the difference between Q Under and Q Excess? I haven't found any explanation in the block information. I thought that IFAS reactors used to have obly one outlet and purge was produced in the posterior secondary settler.
[/quote]
The WEST model incorporates the settler. That's why you have two outgoing fluxes for sludge: Q_Under is the flow you would extract from the clarifier; Q_Excess, the portion of excess sludge.