06-02-2024 - Physics - Slab with fluids on the walls [EN]-[IT]

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~~~ La versione in italiano inizia subito dopo la versione in inglese ~~~


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06-02-2024 - Physics - Slab with fluids on the walls [EN]-[IT]

Slab with fluids on the walls
Basic concepts
The CLapeyron plane is used to represent thermodynamic transformations.
In the abscissas, i.e. x axis, there are the volume values.
In the ordinates, i.e. the y axis, we find the pressure values.
For an isochoric transformation (constant volume thermodynamic transformation) on the Clapeyron plane it is represented by a straight line parallel to the ordinates.
For an adiabatic transformation (transformation that takes place without heat exchange with the outside) the Clapeyron plane will present a rather inclined hyperbola.
For an isothermal transformation (thermodynamic transformation at constant temperature) the Clapeyron plane will present a fairly flat hyperbola, i.e. less inclined than the hyperbola which can represent an adiabatic transformation.
For an isobaric transformation (thermodynamic transformation at constant pressure) the Clapeyron plane will present a straight line parallel to the abscissa axis.

Slab and fluids
In a plate touched on two sides by two moving fluids, an exchange of energy certainly takes place.
in the drawing below the system described above is represented with the plate in the center and the two flows schematized on the faces of the plate.

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In general we can think of a graph with the temperature on the ordinates and it would look like this.

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The previous graph can be seen like this if we think about our plate

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Now, we can think about the system and make an analogy with electrical conduction.
We will therefore have that our system with the plate and the two fluids will appear as follows.

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By studying the system we can arrive at the following equality

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From this last relation we note that if r1 is much smaller than r2 T 0 tends to T fi, which would be the case in which the moving fluids have a very high speed

Conclusion
In a system composed of a plate and two fluids flowing on the two faces, internal and external, the convective resistances tend to zero and the temperature of the fluid will be equal to that of the surface of the plate.

Request
It's never happened to me, but I'm asking you. Have you ever tried to study systems with fluids that have high speeds?



06-02-2024 - Fisica - Lastra con fluidi sulle pareti [EN]-[IT]

Lastra con fluidi sulle pareti
Concetti base
Il piano di CLapeyron viene usato per rappresentare le trasformazioni termodinamiche.
Nelle ascisse, ovvero asse x, ci sono i valori del volume.
Nelle ordinate, ovvero asse y, troviamo invece i valori della pressione.
Per una trasformazione isocora (trasformazione termodinamica a volume costante) sul piano di Clapeyron è rappresentato da una retta parallela alle ordinate.
Per una trasformazione adiabatica (trasformazione che ha luogo senza scambio di calore con l'esterno) il piano di Clapeyron presenterà un iperbole piuttosto inclinata.
Per una trasformazione isoterma (trasformazione termodinamica a temperatura costante) il piano di Clapeyron presenterà un iperbole abbastanza stesa, cioè meno inclinata dell'iperbole che può rappresentare una trasformazione adiabatica.
Per una trasformazione isobara (trasformazione termodinamica a pressione costante) il piano di Clapeyron presenterà una retta parallela all'asse delle ascisse..

Lastra e fluidi
In una lastra lambita su due lati da due fluidi in movimento avviene certamente uno scambio di energia.
nel disegno qui sotto viene rappresentato il sistema descritto sopra con la lastra al centro ed i due flussi schematizzati sulle facce della lastra.

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In generale possiamo pensare ad un grafico con la temperatura sulle ordinate e risulterebbe come segue.

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Il grafico di prima può essere visto così se pensiamo alla nostra lastra

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Ora, possiamo pensare al sistema e creare un'analogia con la conduzione elettrica.
Avremo quindi che il nostro sistema con la lastra ed i due fluidi apparirà come segue.

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Studiando il sistema possiamo arrivare alla seguente uguaglianza

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Da quest'ultima relazione notiamo che se r1 è molto minore di r2 T 0 tende a T fi, che sarebbe il caso in cui i fluidi in movimento hanno una velocità molto alta

Conclusione
In un sistema composto da una lastra e due fluidi che scorrono sulle due facce, interna ed esterna, le resistenze convettive tendono a zero e la temperatura del fluido sarà uguale a quella della superficie della lastra.

Domanda
A me non è mai capitato, ma chiedo a voi. Avete mai provato a studiare dei sistemi con fluidi che hanno velocità elevate?

THE END



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13 comments
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This is an interesting lesson. May I ask if this topic is any way related to topology in mathematics? Have a nice day.

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Unfortunately I couldn't answer if this topic is related to topology in mathematics. Perhaps the most important concept of this article is the understanding that if the speeds of the fluids are very high, the convective resistances tend to zero and the temperature of the fluid will coincide with that of the surface of the plate.

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This is kind of related to the slab features been shown and discussed

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Exactly, all of this is also related to the characteristics of the slab. What we can add is that if the speed of the fluids touching the plate is very high, the convective resistances tend to zero and the temperature of the fluid will be similar to the surface of the plate.

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I’ve never tried to study such a thing in my life
To me, science is interesting but hard and the hard part usually makes me run from it, lol

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I agree that physics is sometimes really difficult to understand, then the topic covered in this post is quite complex and little discussed. I think that the first thing to do is to understand the concept and not understand how the various formulas can be done or carried out. For example, in this case, the main concept is as follows. By analyzing the exchange of energy between two fluids that touch a plate we can say that, if the speeds of the two fluids are very high, the convective resistances tend to zero and the temperature of the fluid will coincide with that of the surface of the plate.

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This type of calculations is always difficult to understand but one thing I quite believe is when you finally understand them, it is always easy to continue from there

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I believe the first objective when studying physics is not knowing how to do the calculations, but the first thing to do is to understand what those calculations say. Then you can try to also try to understand the formulas and manage them. But I repeat, the important thing for me, first of all, is to understand the concept. For example, what can be understood from this article is that if two fluids graze a plate going at very high speeds, the temperature of the fluid will coincide with that of the surface of the plate because the convective resistance tends to zero.

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Non l'ho studiato

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Infatti lo studio dei fluidi e dei loro moti convettivi sono studi molto particolari, però c'è da ammettere che questi studi sono molto usati nel settore del riscaldamento delle abitazioni con termosifoni. Sinceramente altre applicazioni ora non mi vengono in mente, ma credo che ce ne siano altre

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