What is Modelling: Definition and 286 Discussions

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.
Representational models can be broadly divided into the concrete (e.g. physical form) and the abstract (e.g. behavioural patterns, especially as expressed in mathematical form). Of particular importance in the modern context, 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.
In commerce, a model might instead reference a specific version or configuration of a product offering, rather than functioning as a representation of something else.
In taxonomic settings (e.g. biology, architecture, art) a model is sometimes a particular instance of a set of related entities (species, built structures, artistic compositions) chosen as a convenient reference point around which to build discourse; such a model is almost always chosen to typify some central tendency of the group, exemplify the group's defining characteristic, or reify the group's historical lineage.
Kinds of models include:

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  1. J

    I Modelling Liquid Hydrogen Boil-Off Rate

    The relevant thermal conductivity, heat transfer coefficients, and thicknesses along with all other required parameters are known. I have attempted to use the online simulation tool boilFAST to simulate each scenario however, the results show a negative spike in boil-off rate which I don't see...
  2. T

    Need Recommendations for Nuclear Reaction Modelling Software

    Working on a project where I need to model nuclear reactions with different fuel pellet shapes. Does anyone have recommendations for software that's good for this? Any advice or experiences are also welcome!
  3. M

    Engineering Kinematic modelling of a mechanism (General Crank)

    Hi, I was wondering if you could help me with a job at the university that consists of the kinematic modeling of mechanism number 3 in the image attached to this message. I have to set up the constraint equations and then solve the position, velocity and acceleration problem. For now I would...
  4. person123

    My Python Library For Finite Difference Method

    I recently made a Python library for modelling (very basic) finite difference problems. The Github readme goes into details of what it does and how it works, and I put together a Google Colab with some examples (diffusion, advection, water wave refraction) with interactive visuals. I'd love to...
  5. Sciencemaster

    I How can I model squeezed states in 3D optical modelling software?

    I would like to model squeezed light and its evolution (such as when passing through lenses after being generated) using optics software such as OptiFDTD or ZEMAX. However, I don’t see any way to make such states…my plan was to simulate an Optical Parametric Amplifier to generate these states...
  6. W

    Transformer modelling for harmonic studies

    Why transformer core is modeled as resistance even though it is frequency dependent.With increasing frequency current rises. Doesn't it seem capacitive reactance behaviour? Which decrease with increasing omega?
  7. W

    Modelling of tranformer and MV cable for harmonic studies

    For my research project, modelling is needed for dyn5 630 kVA transformer and 20 kV cable NA2XS(F)2Y to do harmonic analysis. For that i need leakage reactance, and resistance of copper losses for transformer. And following parameters for 20 kV cable are also needed. Positive, negative and...
  8. casualguitar

    Modelling of two phase flow in packed bed (continued)

    Previous post linked here, where a model for the two phase flow of air through a packed bed was developed: https://www.physicsforums.com/threads/modelling-of-two-phase-flow-in-packed-bed-using-conservation-equations.1008754/ The first few comments on this new thread will be copies of the...
  9. H

    MATLAB Modelling a Heat Pump with Linear Compressor using MATLAB Simulink

    Hello, I am a final year mechanical engineering student designing a heat pump with a linear compressor for an electric vehicle and have decided to model this using Simulink, I would love some help on the governing equations/formulas needed for each component of the heat pump as well as guidance...
  10. sophiecentaur

    Free simulation software for antenna and feed modelling

    I want to be able to predict the performance of modest (Amateur) Radio Telescope Equipment. Most of what I can find from a basic search will cost a lot of money. (Not surprisingly). I located a free, student, version of CST Suite from Dassault and it appears to be very powerful and can deal...
  11. casualguitar

    Modelling of two phase flow in packed bed using conservation equations

    Previously, I have seen the derivation of the energy conservation equations for simulation of single phase flow in a porous media (a packed bed). These are the energy equations for the solid and fluid respectively: I understand the derivation, however, these equations will only work when the...
  12. Jason-Li

    Comp Sci Seeking Guidance on Working Through Tank Problem with Multiple Tanks

    Hello all I come to again seeking guidance... There is another thread but he seems to have pulled formulas from somewhere other than our learning materials to reach the conclusions. Looking at this question and I can't figure out where to start really, the examples in out learning materials...
  13. NickTheFill

    Modelling the tyre as a spring in a quarter car model

    Hi everyone I've just completed a mechanical engineering degree, and one aspect of the classic 2DoF quarter car model that still bugs me is the representation of the tyre as a linear spring attached to the ground. Does anyone have any experience of modelling the system with the tyre spring...
  14. G

    Modelling Rutherford Scattering - in the school lab

    Hi, New to the forum here! I'm teaching age 16-18 physics in the UK. I was wondering if anyone in here might have experience using equipment that looks like this: https://www.eiscolabs.com/products/alpha-scattering It's a physical analogue of Rutherford's famous experiment: roll ball bearings...
  15. K

    Modelling an interation between two protons

    The image given with the problem: I found the original problem too difficult to solve, so I thought I'd make it easier by first considering the stationary proton as fixed in place. However, this too proved to be way more difficult than I expected. Here's the updated diagram I used in my attempt...
  16. person123

    I Boundary Conditions For Modelling of a Fluid Using Euler's Equations

    Hi! I want to use Euler's equations to model a 2 dimensional, incompressible, non-viscous fluid under steady flow (essentially the simplest case I can think of). I'm trying to use the finite difference method and convert the differential equations into matrices to be solved using MATLAB. I set...
  17. R

    Modelling Heat Transfer for Pulsating Laminar Duct Flow

    Good evening everybody. I am new here I hope it is okay to ask this question here. As part of a project I am trying to examine the effect of a pulsating laminar duct flow on the heat transfer behavior for constant heat flux at the wall for a Newtonian incompressible fluid. As such I am...
  18. G

    I Solving a DE for modelling the spread of an infectious disease

    This DE is related to a mathematical model of the spread of an infectious disease: $$f'\left(x\right)=a\cdot\left[f\left(x\right)-f\left(x-b\right)\right]$$ where a and b are positive constants. I would like some pointers as to how I should begin attempting to solve it.
  19. L

    Help Evaluating Mathematical Modelling of Physical Problems

    I am really struggling with these problems and do not really know where to begin. In most cases I have just defined what the modelling means, e.g A rough surface is one upon which friction acts etc. I would really appreciate some help with suitably answering these questions comprehensively, and...
  20. E

    Modelling assumptions when friction is involved

    Whenever friction exists within a mechanics problem, there must be some dissipation of mechanical energy into thermal energy. However, I'm not sure how we determine which bodies can or cannot possesses thermal energy. Suppose we consider the case of a block sliding down a rough wedge, which is...
  21. A

    MATLAB Catalyst Modelling with MATLAB: Modeling Concentration Profile in Photoreactor

    I have little knowledge of MATLAB. I am trying to model the concentration profile along the photocatalyst film thickness in a photoreactor. Mass Transport takes place by diffusion and the rate of generation of component is given by rA. Boundary conditions: Concentration of the component that is...
  22. HAgdn

    What research designs used on mathematical modelling?

    I am currently conducting a study that proposes a mathematical model. "mathematical model (n): a representation in mathematical terms of the behavior of real devices and objects."[1] The study composes of: AIM of the study: Create a mathematical model that represents a phenomena or happening...
  23. V

    Mathematical modeling of a screw compressor

    I am trying to design a compressor in simulink. the mathematical equations has been modeled. but i just need, is there any relation to find the rate of change of volume with respect to time in compressor. Are there any equations or relations to find the rate of change in volume. As its a...
  24. W

    I Quantum Causal Modelling: Mathematics

    I have been trying to read through the following paper: https://iopscience.iop.org/article/10.1088/1367-2630/18/6/063032/pdf, but am stuck at the parts from page 6 onwards. What is the "approach/formalism" used in the following sections of the paper, and are there any gentle introductions...
  25. haruspex

    I What is the expected value of Cov(x,y)2 in an independent X and Y scenario?

    all the references I can find on the net to justifying a correlation treat it as a matter of judgment, and, quite correctly, that it depends on the application. But it seems to me that one could compare the fit to the data of a horizontal line (i.e. average y) with that of the linear regression...
  26. H

    Partial Differential Equation Mathematical Modelling

    Salutations, I have been trying to approach a modelling case about organism propagation which reproducing with velocity $$\alpha$$ spreading randomly according these equations: $$\frac{du(x,t)}{dt}=k\frac{d^2u}{dx^2} +\alpha u(x,t)\\\ \\ u(x,0)=\delta(x)\\\ \lim\limits_{x \to \pm\infty}...
  27. Nikhil N

    Dynamic modeling of a system and transients of the system

    Consider, I have a dynamic system model for air compressor. Which means I have modeled the system by including its physics. Does this means I also included the transients of the system? What I think is, when i modeled any system with equations, I think that includes the transients. Is it...
  28. Eveflutter

    Math modelling diffrential equation question?

    So there's this question I've to do. I got through until a certain point and now I'm stuck. >-> 1&2The question: The rate of deterioration of a product in a container is proportional to the amount of product present. At time t, the amount of product is x. (i) State the diffrential equation...
  29. akaliuseheal

    How do I calculate the voltage of a diode in a simple electronics circuit?

    Homework Statement It's simple problem but I get stuck while calculating the VD. Currents and voltages in the circuit are required. So V, VD and I Homework EquationsThe Attempt at a Solution Since VA<VK I would assume that diode is OFF and then the diode can be represented by break. Upon...
  30. Alexander350

    Modelling Water Tanks: Solving with Bernoulli Equation

    I tried using the Bernoulli equation to solve this. I took two points at the surface of the water in both the containers and formed this equation: gh_{b}=\frac{1}{2}v^2+gh This is assuming that the velocity of the water in the large tank is approximately zero and using the fact that both the...
  31. CMW328i

    Noise Modelling - Digital communication systems

    Hi all, Teacher here looking for some guidance. I'm teaching a class that I took myself a few years back, and I'm looking at my solution to a problem but I have a random value in my answer (which I know to be correct) but I can't for the life of me remember where this value came from! Can anyone...
  32. R

    How to Connect Coils in Series in Ansys Maxwell 3D?

    Hello everyone, wondering if you can give some help with ansys Maxwell 3D modelling. I'm working on the design of a new type of transformer and according my drawings and calculations I need to physical connect (not mutually-inducted) three coils in the secondary side of the transformer, they...
  33. A

    Help with Python modelling of a particle in a 2D box

    Hello guys, I programmed a physics simulation where a particle with some initial conditions bounces off the walls of a 2d container. The simulation also includes gravity in the y-coordinates. The aim of the project is to produce a visual animation and further on include more particles and...
  34. V

    Why does not this Erdos-Renyi C code work?

    Homework Statement I need to write an Erdos-Renyi random graph, by using the adjacency matrix (or alternatively list) and calculate the fitness of the graph. Definition: G(n, p) is a random graph with n vertices where each possible edge has probability p of existing.Homework Equations The...
  35. F

    Modelling eddy currents in a pendulum

    Hello, I was solving a problem related to Eddie currents recently and I need some help with simulating it numerically. Basically, we have a disc-like copper pendulum entering a region of uniform magnetic flux density B (see diagram). I understand that I need to use Faraday's law: \nabla...
  36. M

    A DFT modelling of graphene, fullerenes, nanotubes etc

    Hi all. Does anyone here have any experience modelling graphitic materials using DFT based software (eg VASP)? I am looking to utilise some simulation results in conjunction with applied research on these materials. The focus is really the applied stuff, and I have very little background in...
  37. G

    Modeling epidemics - solving differential equation

    I am given a modified SIR model in which the rate of decrease of susceptibles S is proportional to the number of susceptibles and the square-root of the number if infectives, I. If the number R of those who have been removed or recovered increases in proportion to the infectives, we have the...
  38. L

    I Chernobyl Dose Model & Estimates

    Hello all, I've been tasked with developing a model for dose received from the Chernobyl Accident. I'm struggling a little to find dose estimates from which I can extrapolate back to find the initial dose received. Does anyone have any references that they can point me towards? I believe there...
  39. H

    I Why is DNS more computationally expensive than k-ε?

    In the modelling of turbulent flows, DNS is often too computationally expensive. Therefore, we take a 'statistical' approach and use mean flow equations, which require closure on account of the Reynolds stress. One way to do that is through the Eddy Viscosity Hypothesis, and one of the ways of...
  40. J

    Efficiently Running Multiple MCNP Simulations with Variable Source Positions

    I'm currently working on a project using mcnp to model a HPGe detector with a Co-60 source. I have defined my cells and got my geometry spot on but the project requires me to move the source around about 50 different positions relative to the detector. I was wondering if there was any way to...
  41. A

    What is a positive sequence model of an induction machine?

    I'm trying to understand a 3 phase induction machine model used as a generator in a Doubly Fed Induction Generator (DFIG) arrangement in Simulink. In this model for the induction generator component, they have stated that the model is a "Positive sequence model" of the induction generator...
  42. Q

    I Modelling Decoherence as a Transition Out of Subspace

    Modelling the onset of decoherence in a subspace as a transition from this subspace http://www.ba.infn.it/~pascazio/publications/sudarshan_seven_quests.pdf (Section 10 is relevant) I am currently reading papers discussing the Zeno Effect. The linked paper discusses modelling a transition out of...
  43. BubblesAreUs

    How can I model a temperature change using MATLAB?

    Homework Statement Modelling the following equation: k = Delta Q / t Homework Equations Q = T2 - T1 = -40 (fixed) t = Delta Q / k. I need to find t. k can be floating so I suppose 0 to 10 minutes with 0.5 increments The Attempt at a Solution I don't have MATLAB on me at the moment...
  44. oMattz

    Modelling the height of a block up a slope with time

    1. Homework Statement A block, of mass M1, on the rough slope shown is attached to another mass M2 by a light, inextensible string which passes over a frictionless pulley as shown in the diagram (the coefficient of friction between the block and the slope is u ). The block is released from...
  45. T

    Describing elliptic orbit as a parametric function

    Hi PF I've beent rying to model the lunar orbit around the sun (cardioide) as a parametric function, but have run into a problem. f(t) = r(t) : x = a cos(ωt) y = b sin(ωt) z = k t The angular frequency ω as well as the distance from to the center varies around the orbit. Is...
  46. G

    Experimental data modelling off-road vehicle travel

    Hi everyone, I am looking for any available experimental data which models off-road vehicle travel in clay and measures tyre and soil parameters. Parameters I am looking for include pull, torque, shear strength of the soil, sinkage, slip and deflection. If anyone knows of any available raw data...
  47. 0

    Consequences of Choosing Incorrect Variables in BuckinghamPi

    This question arose as I was studying mathematical modeling in fluid mechanics. It was posted to math.stackexchange, but there a was a lack of response, probably due to the applied nature of the problem. One form of the Buckingham Pi Theorem says that for nn variables with kk dimensions, the...
  48. M

    Major in Physics vs Statistical Modelling

    Hello! I'm a student in my 3rd year in physics, and due to low demand for physicits in my country. I'm planning to switch for something else. Right now, I have the opportunity to join a bachelor in Statistical Modelling and Computer Science. I love both majors, and I like how the second one...
  49. A

    Finding the Fermi Level with Theoretical Modelling

    I'm making some theoretical modelling for a system, which is effectively 1d in the sense that it is much longer the wide. This means (like in model for quantized conductance) that the energy bands are parabolas with a spacing equal to the energy difference between the ground state, first excited...