Functional Modelling and elements

Multilevel Flow Modelling(MFM) is a functional modelling language for representing the mass and energy of process systems. The developed language is capable of representing the functional intentions of a system and their dependencies on each other to achieve high-level goals.

Each function is modelled as either a mass- or an energy-balance to describe the function's behaviour with qualitative physics. To do so, the model must follow a syntax which is a set of rules, that ensures that any model output from the reasoning is meaningful. Note, that this does not mean that any model result is necessarily a valid representation of the physical system, which requires a more rigorous process.

 

When modelling a system, the system should be decomposed into a hierarchy with the following model elements:

These elements are used for creating a model structure to enable modelling a causal dependence between functions and systems, and to enable model modularization. The flow and control structures should be placed inside the Main Equipment box, which should be placed inside the system box. 

Inside the mass and energy flow structures, and the control structure, a function can be modelled by using the set of model elements below. They consist of a set of flow functions, objectives, controllers and different types of relations.

Flow functions	Source	Transport	Barrier	Storage	Balance	Sink
Influence relations	Influencer	Participant	Sharing
Function-function Means-end relations	Producer-Product	Inverse-Producer-Product	Mediate
Function-objective Means-end relations	Produce	Maintain	Suppress	Destroy
Objectives	Target	Hazard	AND gate	NOR gate
Condition relations	Enable	Disable
Control relations	Actuate
Control functions	Produce	Maintain	Supress	Destroy