Modelling Definition and 288 Threads

I happen to be modelling PEMFC and accounted for various transport equation including mass, heat, species and charge. I was able to validate my stationary model based on a published reference. In validating its voltage dynamic response, I was expecting at a potentiometric conditions that an...

does anyone know the derivation of the general solution of the nonhomogeneous equation shown in the image (book name: Devendra K. Chaturvedi - Modeling and Simulation of Systems Using MATLAB and Simulink -CRC Press (2010))

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...

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!

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...

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...

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...

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?

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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.

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...

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...

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...

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...

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...

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...

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...

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}...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...