The down side is everything explodes exponentially - setup time, mesh count, solve time; and we usually get worse results than more focused simulations because we can't squeeze enough detail in across the board.
It generally starts because some manager hears that we've created 8 different specialized models of something due to different areas of interest, and has the bright idea of "lets just create a single super-accurate model we can use for everything". I've been fighting against them my entire career, although 10 years ago it was "virtual mockups"
The next buzzword in the pipeline seems to be "virtual lab" which I can't figure out either. I've been simulating laboratory tests for over a decade and no one can explain to me why that isn't exactly what we're already doing.
None of this is to say that this team isn't doing great work, but somewhere along the way it got wrapped up in some marketing nonsense.
Edit: Restructured my reply to better address OPs question.
"Light fields" is one that always annoyed me. People who are apparently unaware of centuries of knowledge and methods in electromagnetism, developing "new" ways to solve problems crudely. That's great if they can make some cool new imaging system, but is it research deserving of long-term high-risk funding? It's just something that anyone skilled in optics can work out if they thought to build it.
So you can have sensor and measurement data from the real thing be streamed to the model in (ideally) real-time, you can make decisions off of the state of the model, and have those decisions be sent back out into the real world to make a change happen.
The specific wording of digital twins originated from a report discussing innovations in manufacturing, but I find that railway systems and operations make for some of the best examples to explain the concept, because they manage a diverse set of physical assets over which they have partial direct control, and apply conceptual processes on top of them.
Here's three assorted writings [1][2][3] that explain how railways would benefit from this.
[1] https://www.anylogic.com/digital-twin-of-rail-network-for-tr...
[2] https://www.railwayage.com/analytics/how-digital-twins-suppo...
[3] https://www.railwayage.com/analytics/realizing-the-potential...
I work as a Computational Researcher at Stanford Med. My work is quite literally translating 3D scans of the eyes (read MRI) into "digital twins" (read FEA Models).
I think that there is a subtlety in differentiating a digital twin from a model/simulation in intent. Our intent is to quite literally figure out how to use the digital twin specifically, NOT the scan that it is based on, as a way to replace more invasive diagnostics.
Of course, in the process, we figure out more about diagnosing medical problems as a function of just the scans themselves too.
Either way I wouldn't think too much about it. Tech is full of these things. I have been working with AI and neural networks for years before it was called Machine Learning. Now I'm forced to use the term ML to sound relevant even though it is the same thing.
For GE's digital twins in the jet engines, they will build a high fidelity representation of the each individual engine based on as built parts, and then they will simulate every flight based on accelerometers, force sensors, humidity sensors, temperature and pressure sensors which they have placed in the engine. This is different from a general model or simulation which will build a model from CAD and then have a series of expected flight simulations and use that to predict life of the engine.
I work with digital twins in chemical manufacturing, and there the term is directly coupled with Model Predictive Control. The basic idea is that you build a model of the system (e.g. a chemical plant) you want to control, use that model to optimize controller behavior, apply the results to real controllers in the real system, and then sample the system to reground the model. Rinse, repeat. Such a model is called the "digital twin" of the real system - the idea is that it exists next to the system and is continuously updated to match the real world.
> Healthcare is recognized as an industry being disrupted by the digital twin technology.[45][34] The concept of digital twin in the healthcare industry was originally proposed and first used in product or equipment prognostics.[34] With a digital twin, lives can be improved in terms of medical health, sports and education by taking a more data-driven approach to healthcare.