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Andrey Varlamov SPIN-CNR, Italy in collaboration with Attilio Rigamonti, Giuseppe Balestrino Physics in a kitchen.

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Presentation on theme: "Andrey Varlamov SPIN-CNR, Italy in collaboration with Attilio Rigamonti, Giuseppe Balestrino Physics in a kitchen."— Presentation transcript:

1 Andrey Varlamov SPIN-CNR, Italy in collaboration with Attilio Rigamonti, Giuseppe Balestrino Physics in a kitchen

2 General formula for the cooking time Heat flow D t cook = aD 2 +b

3 1. Egg alla “coque” T cook ~ M 2/3 log e [ 0.76(T egg -T water )/ (T yolk -T water ) ]

4 t3t3 M2M2 Mass (pounds) Cooking time (hours) The Thanksgiving day turkey secret t cook = aM 2/3 + b

5 3. Physics of Pasta Het flow and water diffusion Cooking time: t=a D 2 +b Heat transfer: Water diffusion:

6 Tipo di pastaDiametro est. D Diametro int. d Tempo di cottura sper. Tempo di cottura teor. Capellini n mm--3 min2 min Spaghettini n mm -- 5 min5.0 min Spaghetti n mm--8 min8.2 min Vermicelli n mm--11 min10.7 min Vermicelli n mm--13 min13.0 min Bucatini2.70 mm1mm8 min 25 min ?! a = 3.8 min / mm 2 b = - 3 min The table of cooking times for the different types of spaghetti t=aD 2 +b

7 The case of bucatini requires the particular treatment. The correct formula is: t=a(D-d) 2 +b For bucatini: t b =8.2 min ! P=ρgh=2σ/r min d min =2 r min ~ 4σ/ ρgh h=2cm, σ=0.05 N/m g=9.8 m/s 2 d min ~ 1mm

8 Fall down of our simple theory for too thin pasta Capellini: d = 1.15 mm t cap = 3.8 [ 1.15 ] ≈ 2 min a D 2 +b=0 D cr =√|b|/a≈0.85 mm

9 Spaghetti: knotting a) Help in the industrial research

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11 Spaghetti: knotting

12 Why spaghetti do not break into two pieces? The arc experiment Equivalent catapult experiment When dry spaghetto is bent beyond its critical curvature it often breaks more than into two pieces, typically 3 or 4. Ig Nobel 2006 in Physique : Basile Audoly et Sébastien Neukirch de l'université Pierre et Marie Curie (Paris), pour leurs recherches expliquant pourquoi les spaghettis secs se cassent généralement en plus de deux morceaux.

13 The breaking dynamics: (B.Audoli, S.Neukirch, PRL, August 2005)

14 When the rod is broken, one could expect that the generated elastic waves help to both pieces of rod to relax to equilibrium. Invece, si verifica che queste onde aumentano lo stress locale, rendendo probabile la rottura della bacchetta anche in altri punti. Ne consegue una frammentazione.

15 The breaking dynamics Fast camera

16 Fast removing of the constrain from the extremity of the half-rod results in generation of the elastic wave: Simul.mov

17 Viscosity versus pasta size S g L


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