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| − | <small>Subpage contents<BR>
| + | This project has migrated over to '''github'''. |
| − | > [[TestMarupio/glossary|glossary]]<BR>
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| − | > [[TestMarupio/In depth|In depth]]<BR>
| + | |
| − | > [[TestMarupio/multiControlDict|multiControlDict]]<BR></small>
| + | |
| − | <small>I am currently travelling and working offline. Updates will appear when I return (July 4th) or if I get internet access</small><br>
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| − | '''multiSolver''' is a master control class that allows you to create a [[TestMarupio/glossary#superSolver|superSolver]] composed of multiple solvers within a [[TestMarupio/glossary#superLoop|superLoop]]. All solvers operate on the same dataset in sequence. For example: | + | |
| | | | |
| − | # <tt>icoFoam</tt> - runs to completion;
| + | '''''[http://github.com/Marupio/multiSolver/wiki Click here for the new website.]''''' |
| − | # data is handed over to <tt>scalarTransportFoam</tt>;
| + | |
| − | # <tt>scalarTransportFoam</tt> - runs to completion;
| + | |
| − | # data is handed back to <tt>icoFoam</tt>, and the [[TestMarupio/glossary#superLoop|superLoop]] repeats.
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| | | | |
| − | Features:
| + | http://github.com/Marupio/multiSolver/wiki |
| − | * '''Single case directory''' - the settings for all solvers are stored within a ''single'' case directory using a "[[TestMarupio/glossary#multiDict|multiDict]]" dictionary format.
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| − | | + | |
| − | * '''Easy data management''' - All the data output is sorted into subdirectories corresponding to the solver, and can be loaded / unloaded using the [[TestMarupio/multiPost|multiPost]] utility.
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| − | | + | |
| − | * '''Store data''' - Not all solvers have to use all the fields. Rather, they can "store" an unneeded field, leaving more memory and disk space. The next solver retrieves all stored fields, and no data is lost.
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| − | | + | |
| − | <!--* '''Flexibility''' - The main control dictionary, [[TestMarupio/multiControlDict|multiControlDict]] has -->
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| − | | + | |
| − | ... still in progress ...
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| − | | + | |
| − | The settings for each solver are all stored within a single case directory using a [[TestMarupio/glossary#multiDict|multiDict]] format. All the data output is sorted into subdirectories corresponding to the solver, and can be retrieved for easy data management. This kind of behaviour is very useful for:
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| − | | + | |
| − | * multi-step processes to be modelled within a single application, e.g. fluid injection, followed by settling;
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| − | * modelling of a flow problem characterized by two different timescales, e.g. stirring with biochemical reactions; and
| + | |
| − | * changing boundary conditions mid-run.
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| − | | + | |
| − | It turns out this type of behaviour is difficult, if not impossible, to implement in OpenFOAM without '''multiSolver'''.
| + | |
| − | | + | |
| − | == Why is it needed? ==
| + | |
| − | A fundamental assumption in the design of OpenFOAM is the existence of a universal time. Therefore the time object is the top-level [[objectRegistry|object registry]], which means it controls the database for every solver. This design works for nearly all simulations imaginable, except for multi-step simulations.
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| − | | + | |
| − | :'''''Multi-step simulation'''''
| + | |
| − | :Here, a multi-step simulation is a simulation where:
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| − | | + | |
| − | :# one solver is run to completion;
| + | |
| − | :# the dataset is handed over to another solver;
| + | |
| − | :# this solver is run to completion; and
| + | |
| − | :# repeat from step #2 as many times as necessary for as many different solvers as necessary.
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| − | | + | |
| − | Trying to accomplish this within the existing '''runTime''' framework is problematic. '''multiSolver''' achieves this behaviour neatly.
| + | |
| − | | + | |
| − | == When do you need it? ==
| + | |
| − | The '''runTime''' framework can handle nearly every simulation imaginable, but there are situations where '''multiSolver''' will make things much easier. For example:
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| − | | + | |
| − | * If you are modelling a multi-step process, with clearly defined changes in boundary-conditions over time; or
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| − | * If you are modelling a single problem with internal processes characterized by vastly different timescales.
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| − | | + | |
| − | Basically, if you find yourself:
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| − | | + | |
| − | * frequently copying data between case directories;
| + | |
| − | * frequently stopping and changing the simulation details, then restarting; or
| + | |
| − | * using <tt>runTime++</tt> more than once in your solver,
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| − | | + | |
| − | then '''multiSolver''' might help you.
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| − | | + | |
| − | === Parallel runs and mesh motion not fully supported yet ===
| + | |
| − | '''NOTE:''' At this time, '''multiSolver''' does not support parallel runs at all; and mesh motion is allowed, provided the mesh returns to its original position between solvers. This functionality is planned for the future.
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| − | | + | |
| − | == How do you program applications with it? ==
| + | |
| − | | + | |
| − | === Overview ===
| + | |
| − | <span id="simpleExample">Here's a quick overview of how to program applications with multiSolver.
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| − | | + | |
| − | # Download and comile it;
| + | |
| − | # Write (or choose from existing) solvers that your [[TestMarupio/glossary#superSolver|superSolver]] will use;
| + | |
| − | # Set up the createFields for each solver;
| + | |
| − | # Add <tt>#include "multiSolver.H"</tt> to the top;
| + | |
| − | # Between <tt>#include "setRootCase.H"</tt> and <tt>#include "createTime.H"</tt> add:
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| − | # include "createMultiRun.H"
| + | |
| − | solverDomain = "nameOfFirstSolver";
| + | |
| − | # include "setSolverDomain.H"
| + | |
| − | 6. Between each solver, add the lines:
| + | |
| − | solverDomain = "nameOfNextSolver";
| + | |
| − | # include "setSolverDomain.H"
| + | |
| − | :where <tt>nameOfNextSovler</tt> is a [[TestMarupio/glossary#solverDomainName|solverDomainName]]<BR>
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| − | 7. From each solver, include everything from <tt>#include "createTime.H"</tt> to just before <tt>return 0;</tt><BR>
| + | |
| − | 8. At the end, add:
| + | |
| − | # include "endMultiSolver.H"
| + | |
| − | return 0;</span>
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| − | | + | |
| − | === More details ===
| + | |
| − | The example above is a simple use of '''multiSolver''', but it is capable of more. For more details see [[TestMarupio/In depth]].
| + | |
| − | | + | |
| − | == How do you run simulations with it? ==
| + | |
| − | Here is a brief overview of how to work with a '''multiSolver'''-enabled application.
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| − | | + | |
| − | === MultiControlDict ===
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| − | The [[TestMarupio/multiControlDict|multiControlDict]][[TestMarupio/glossary#multiControlDict|(glossary)]] is the '''multiSolver''' analogue of the <tt>controlDict</tt>. The <tt>controlDict</tt> is auto-generated based on the content of this file. The [[TestMarupio/multiControlDict|multiControlDict]] is the main control dictionary and therefore it does not conform to the format of a regular [[#multiDicts|multiDict]][[TestMarupio/glossary#multiDict|(glossary)]]. For the full break-down of all settings and options available in the multiControlDict, see [[TestMarupio/multiControlDict|multiControlDict]].
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| − | | + | |
| − | === MultiDicts ===
| + | |
| − | A regular solver reads information from various dictionary files, and these affect its behaviour. When using '''multiSolver''', there will be dictionaries whose values need to be ''different'' for each [[TestMarupio/glossary#solverDomain|solverDomain]]. To specify this behaviour, a [[TestMarupio/glossary#multiDict|multiDict]] is used.
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| − | | + | |
| − | A [[TestMarupio/glossary#multiDict|multiDict]] has the following structure:
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| − | dictionaryName fvSchemes;
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| − |
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| − | multiSolver
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| − | {
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| − | sovlerDomainName1 // this is the [[TestMarupio/glossary#solverDomain|solverDomain]] name
| + | |
| − | {
| + | |
| − | // settings for the first solver go here
| + | |
| − | }
| + | |
| − | solverDomainName2 // another [[TestMarupio/glossary#solverDomain|solverDomain]] name
| + | |
| − | {
| + | |
| − | // settings for the second solver go here
| + | |
| − | }
| + | |
| − | default // optional
| + | |
| − | {
| + | |
| − | // default settings go here
| + | |
| − | // these are loaded first, then overwritten by solverName (above)
| + | |
| − | // solvers whose names are not listed above inherit only these settings, or none at all if default is absent
| + | |
| − | }
| + | |
| − | }
| + | |
| − | | + | |
| − | === Boundary conditions and initial values ===
| + | |
| − | The boundary conditions and initial values are located in:
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| − | | + | |
| − | :<tt>case/multiSolver/<nowiki>[</nowiki>[[TestMarupio/glossary#solverDomainName|solverDomainName]]<nowiki>]</nowiki>/0/0</tt>
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| − | | + | |
| − | This is the analogue of the <tt>case/0</tt> directory, except there is one for every [[TestMarupio/glossary#solverDomain|solverDomain]]. Unlike in a regular simulation, '''multiSolver''' will ''always'' refer to the boundary conditions located in <tt>0/0</tt>.
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| − | | + | |
| − | '''multiSolver''' allows the boundary conditions to change between [[TestMarupio/glossary#solverDomain|solverDomains]]. To accomplish this, '''multiSolver''' will use the ''boundaryField'' specified in <tt><nowiki>[</nowiki>[[TestMarupio/glossary#solverDomainName|solverDomainName]]<nowiki>]</nowiki>/0/0</tt> and copy over the latest ''internalField'' (from the previous [[TestMarupio/glossary#solverDomain|solverDomain]]).
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| − | | + | |
| − | === Output Data ===
| + | |
| − | The data is sorted into [[TestMarupio/glossary#superLoop|superLoop]] subdirectories within subdirectories named after the [[TestMarupio/glossary#solverDomain|solverDomain]]:
| + | |
| − | | + | |
| − | :<tt>case/multiSolver/<nowiki>[</nowiki>[[TestMarupio/glossary#solverDomainName|solverDomainName]]<nowiki>]</nowiki>/<nowiki>[</nowiki>[[TestMarupio/glossary#superLoopIndex|superLoopIndex]]<nowiki>]</nowiki>/[timeValue]</tt>
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| − | | + | |
| − | The standard location of <tt>case/[timeValue]</tt> is used as a temporary loading area, mostly for post-processing.
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| − | | + | |
| − | === Post-processing ===
| + | |
| − | OpenFOAM is hard-coded to look for data in the <tt>case/[time]</tt> directories. In order to post-process (including sampling, and data conversion) the data needs to be there. To accomplish this,
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| − | | + | |
| − | === Runtime Modification ===
| + | |
| − | There are two levels of runtime modification: within a [[TestMarupio/glossary#solverDomain|solverDomain]], and globally.
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| − | | + | |
| − | * Editting a standard dictionary (e.g. <tt>controlDict</tt>, or <tt>transportProperties</tt> applies to a [[TestMarupio/glossary#solverDomain|solverDomain]]. Its effect depends on whether that solver has <tt>runTimeModifiable</tt> enabled. This happens at the end of a solver iteration. However, these changes will be lost in the next [[TestMarupio/glossary#superLoop|superLoop]] when the same [[TestMarupio/glossary#solverDomain|solverDomain]] is initialized.
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| − | | + | |
| − | * Editting a [[TestMarupio/glossary#multiDict|multiDict]] dictionary applies globally. This is goverend by <tt>multiDictsRunTimeModifiable</tt> setting in the [[multSolver/multiControlDict|multiControlDict]], but these modifications do not take place until the next [[TestMarupio/glossary#solverDomain|solverDomain]] is initialized. However, these changes are permanent.
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| − | | + | |
| − | === Local time and Global time ===
| + | |
| − | A fundamental principle of '''multiSolver''' is that time is independent between [[TestMarupio/glossary#solverDomain|solverDomains]]. (If this causes you apprehension, don't worry, the default behaviour uses a standard global time.)
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| − | | + | |
| − | == How does it work? ==
| + | |
| − | OpenFOAM is incredibly flexible, and easily extensible, but implementing a change of this kind challenged its founding assumptions. Therefore, the flexibility was not there on level it needed to be, leaving little option but to use a ''top-level wrapper'' implementation.
| + | |
| − | | + | |
| − | :A ''wrapper'' encloses the targeted object in a class that gives it the environment it expects to operate, while simultaneously presenting a different environment to other objects interfacing with it. At the ''top-level'', the "other objects" are users. (Strictly speaking, at the code-level, '''multiSolver''' is not a true wrapper since it doesn't include an "OpenFOAM solver" as a ''member variable'', but it is in principle.)
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| − | | + | |
| − | '''multiSolver''' works by ''mutating'' the case directory into what each solver requires. A transient solver will see the correct <tt>ddtSchemes</tt> setting in <tt>fvSchemes</tt>; likewise a steady state solver will see <tt>steadyState</tt> for <tt>ddtSchemes</tt>. This is the purpose of the [[#multiDicts|multiDict]][[TestMarupio/glossary#multiDict|(glossary)]] dictionary format.
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| − | | + | |
| − | The data output and input are hard-coded to the <tt>case/[timeValue]</tt> directory. Therefore, when '''multiSolver''' initializes the next [[TestMarupio/glossary#solverDomain|solverDomain]], it archives the existing output into the correct directory at <tt>case/multiSolver/<nowiki>[</nowiki>[[TestMarupio/glossary#solverDomainName|solverDomainName]]<nowiki>]</nowiki>/<nowiki>[</nowiki>[[TestMarupio/glossary#superLoopIndex|superLoopIndex]]<nowiki>]</nowiki>/[timeValue]
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| − | [[Category:Contribution]]
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