Editing Model (section)

===Physical model===
[[File:model.village.arp.750pix.jpg|thumb|Part of the one-ninth [[scale model]] of [[Bourton-on-the-Water]] at Bourton-on-the-Water, [[Gloucestershire]], England]]

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 representation of an [[physical object|object]], person or [[system]]. The object being modelled may be small (e.g., an [[atom]]) or large (e.g., the [[Solar System]]) or life-size (e.g., a [[Model (person)|fashion model]] displaying clothes for similarly-built potential customers). 

The [[geometry]] of the model and the object it represents are often [[Similarity (geometry)|similar]] in the sense that one is a [[scale (ratio)|rescaling]] of the other. 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]] to enhance a region's mountains.

An architectural model permits visualization of internal relationships within the structure or external relationships of the structure to the environment.  Another use is as a [[toy]].

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 engineering|hydraulic structures]]. [[Wind tunnel]] and [[Water tunnel (hydrodynamic)|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]]). In the pre-computer era, the UK economy was modelled with the hydraulic model [[MONIAC]], to predict for example the effect of tax rises on employment. 
<gallery>
File:MONIAC computer.jpg|Water-powered model of the UK economy – [[Phillips Machine|MONIAC]] in the Science Museum, London
File:Hannah Harper 2.jpg|Female model demonstrating [[brassiere]] for similarly-built potential buyers
File:Models of battle at australian war memorial museum.jpg|Model of a war scene — [[Australian War Memorial]], Canberra
File:USDA-ARS Guinea Pig.jpg|left|upright|[[Guinea pig]] used as animal model for studying human [[leptospirosis]]
File:MD-11 12ft Wind Tunnel Test.jpg|[[NASA]] wind tunnel with the scale model of an aeroplane|alt=https://www.nasa.gov/sites/default/files/styles/side_image/public/thumbnails/image/edu_wind_tunnels_1.jpg?itok=pZg9nFzN
</gallery>