A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Models can be divided into physical models (e.g. a model plane) and abstract models (e.g. mathematical expressions describing behavioural patterns). Abstract or conceptual models are central to philosophy of science, as almost every scientific theory effectively embeds some kind of model of the physical or human sphere.
Types of models include:
A physical model (most commonly referred to simply as a model but in this context distinguished from a conceptual model) is a smaller or larger physical copy of an object. The object being modelled may be small (for example, an atom) or large (for example, the Solar System). In some sense, a physical model "is always the reification of some conceptual model; the conceptual model is conceived ahead as the blueprint of the physical one", which is then constructed as conceived.
The geometry of the model and the object it represents are often similar in the sense that one is a rescaling of the other; in such cases, the scale is an important characteristic. However, in many cases the similarity is only approximate or even intentionally distorted. Sometimes the distortion is systematic (e.g., a fixed scale horizontally and a larger fixed scale vertically when modelling topography of a large area, as opposed to a model of a smaller mountain region, which may well use the same scale horizontally and vertically, showing the true slopes).
Physical models allow visualization, from examining the model, of information about the thing the model represents. A model can be a physical object such as an architectural model of a building. Uses of an architectural model include visualization of internal relationships within the structure or external relationships of the structure to the environment. Other uses of models in this sense are as toys.
Instrumented physical models are an effective way of investigating fluid flows for Engineering design. Physical models are often coupled with Computational Fluid Dynamics models to optimize the design of equipment and processes. This includes external flow such as around buildings, vehicles, people, or hydraulic structures. Wind Tunnel and Water Tunnel testing is often used for these design efforts. Instrumented physical models can also examine internal flows, for the design of ductwork systems, pollution control equipment, food processing machines, and mixing vessels. Transparent flow models are used in this case to observe the detailed flow phenomenon. These models are scaled in terms of both geometry and important forces, for example, using Froude number or Reynolds number scaling (see Similitude).
A physical model of something large is usually smaller, and of something very small is larger. A physical model of something that can move, like a vehicle or machine, may be completely static, or have parts that can be moved manually, or be powered. A physical model may show inner parts that are normally not visible. The purpose of a physical model on a smaller scale may be to have a better overview, for testing purposes, as hobby or toy. The purpose of a physical model on a larger scale may be to see the structure of things that are normally too small to see properly or to see at all, for example, a model of an insect or of a molecule.
A physical model of an animal shows the animals physical composition without it walking or flying away, and without danger, and if the real animal is not available. A soft model of an animal is popular among children and some adults as cuddly toy.
Some of the examples of Physical models:
- Model airplane
- Model car
- Model railway
- Model rocket
- Model house
- Model (art), a person posing for an artist, e.g. a 15th-century criminal representing the biblical Judas in Leonardo da Vinci's painting The Last Supper
- Model (person), a person who serves as a template for others to copy, often in the context of advertising commercial products
- Model (product), a particular design of a product offered by its manufacturer
- Car model, a particular design of vehicle sold by a manufacturer
- Model organism (often shortened to model), a non-human species that is studied to understand biological phenomena present in other related organisms, e.g. a guinea pig starved of vitamin C to study scurvy, an experiment that would be immoral to conduct on a person
- Model (mimicry), a species that is mimicked by another species
A conceptual model is a theoretical representation of a system, e.g. a set of equations attempting to describe the workings of the atmosphere for the purpose of weather forecasting. Conceptual models may be a representation of a system. It consists of concepts used to help people know, understand, or simulate a subject the model represents. The term may refer to models that are formed after a conceptualization or generalization process. Conceptual models are often abstractions of things in the real world, whether physical or social. Semantic studies are relevant to various stages of concept formation. Semantics is basically about concepts, the meaning that thinking beings give to various elements of their experience.
- Conceptual model (computer science), a representation of entities and their relationships
- Mathematical model, a description of a system using mathematical concepts and language
- Economic model, a theoretical construct representing economic processes
- Statistical model, a mathematical model that usually specifies the relationship between one or more random variables and other non-random variables
- Model (CGI), a mathematical representation of any surface of an object in three dimensions via specialized software
- Model (logic), a set along with a collection of finitary operations, and relations that are defined on it, satisfying a given collection of axioms
- Model (MVC), the central component of the model–view–controller software design pattern
- Standard model (disambiguation)
- Medical model, a proposed "set of procedures in which all doctors are trained"
- Model act, a law drafted centrally to be disseminated and proposed for enactment in multiple independent legislatures
- Merriam-Webster, Merriam-Webster's Collegiate Dictionary, Merriam-Webster.
- Tatomir, A.; et al. (2018). "Conceptual model development using a generic Features, Events, and Processes (FEP) database for assessing the potential impact of hydraulic fracturing on groundwater aquifers". Advances in Geosciences. 45: 185–192. Bibcode:2018AdG....45..185T. doi:10.5194/adgeo-45-185-2018.
- Ibrahim A. Halloun, Modeling Theory in Science Education (2007), p. 36.
- Media related to Physical models at Wikimedia Commons