Nombre de Lundquist

El nombre de Lundquist $(Lu)$ és un nombre adimensional utilitzat en la mecànica de fluids i, més precisament, en magnetohidrodinàmica i en la física del plasma. S'utilitza per caracteritzar les ones d'Alfvén unidireccionals.^[1] Correspon a la relació de la velocitat d'Alfvén a la velocitat de difusió resistiva.^[2]

Aquest nombre porta el nom del físic suec Stig A. S. Lundquist.^[3] També s'utilitza el símbol $S$ per a representar aquest nombre a la literatura científica.

Definició

El nombre de Lundquist es defineix

$Lu=\sigma \,B\,l\left({\frac {\mu _{e}}{\rho }}\right)^{0{,}5}$

amb :

$\sigma$ = conductivitat elèctrica
$l$ = gruix de la capa de fluid
$\rho$ = densitat
$\mu _{e}$ = permeabilitat magnètica
$B$ = densitat del camp magnètic

Els nombres de Lundquist alts indiquen plasmes altament conductors, mentre que els nombres de Lundquist baixos indiquen més plasmes resistius. Els experiments amb plasma de laboratori solen tenir nombres de Lundquist entre $10^{2}-10^{8}$ , mentre que en situacions astrofísiques el nombre de Lundquist pot ser més gran que $10^{20}$ . Les consideracions del nombre de Lundquist són especialment importants en la reconnexió magnètica.

Referències

↑ Hall, Carl W. Laws and Models: Science, Engineering and Technology (en anglès). Boca Raton: CRC Press, 2000. ISBN 8449320186.
↑ Boyd, T.J.; Sanderson, J.J.. The Physics of Plasma (en anglès). Cambridge University Press, 2003, p. 140. ISBN 0521459125.
↑ Massey, Bernard Stanford. Measures in science and engineering : their expression, relation and interpretation (en anglès). Ellis Horwood Limited, 1986. ISBN 0853126070.

Bibliografia

Priest, Eric; Forbes, Terry «Magnetic Reconnection» ( PDF) (en anglès). Cambridge University Press, 2000.

Vegeu també

Nombre de Reynolds magnètic $(Re_{m})$

Nombres adimensionals de la mecànica de fluids

Absorció (Ab) • Acceleració (Ac) • Alfven (Al) • Arquimedes (Ar) • Atwood (A) • Bagnold (Ba) • Bansen (Ba) • Bejan (Be) • Best (X) • Bingham (Bm) • Biot (Bi) • Blake (Bl) • Bodenstein (Bo) • Boltzmann (Bo) • Bond (Bo) • Boussinesq (Bo) • Brenner (Br) • Brinkman (Br) • Bulygin (Bu) • Cameron (Ca) • Capil·lar (Ca) • Capil·laritat (Cap) • Cauchy (Ca) • Cavitació (

{\sigma }_{c}

) • Chandrasekhar (Q) • Clausius (Cl) • Condensació (Co) • Cowling (Co) • Crocco (Cr) • Damköhler (Da) • Darcy (Da) • Dean (D) • Deborah (De) • Dukhin (Du) • Eckert (Ec) • Ekman (Ek) • Ellis (El) • Elsasser (El) / (

\Lambda

) • Eötvös (Eo) • Euler (Eu) • Fedorov (Fe) • Froude (Fr) • Galilei (Ga) • Görtler (G) • Goucher (Go) • Graetz (Gz) • Grashof (Gr) • Gukhman (Gu) • Hagen (Hg) • Hartmann (Ha) • Hatta (Ha) • Hedström (He) • Hersey (Hs) • Iribarren (Ir) / (ξ) • Jeffreys (Je) • Joule (Jo) • Karlovitz (Ka) • Keulegan-Carpenter (Kc) • Nombre de Kirpitxiov (transferència de calor i massa) (Ki) • Nombre de Kirpitxiov (flux) (Kir) • Knudsen (Kn) • Kutateladze (K) • Laplace (La) • Lewis (Le) • Lundquist (Lu) • Mach (M) / (Ma) • Mach crític (Mcr) / (M^*) • Marangoni (Ma) • Morton (Mo) • Newton (Np) • Nusselt (Nu) • Ohnesorge (Oh) • Péclet (Pe) • Potència (Np) • Prandtl (Pr) • Prandtl magnètic (Pr_m) • Prandtl turbulent (Pr_t) • Rayleigh (Ra) • Reech (Re) • Reynolds (Re) • Reynolds magnètic (Re_m) • Richardson (Ri) • Roshko (Ro) • Rossby (Ro) • Rouse (P) / (Z) • Ruark (Ru) • Schiller (Sch) • Schmidt (Sc) • Scruton (Sc) • Sherwood (Sh) • Shields (

\tau _{\ast }

) / (

\theta

) • Sommerfeld (S) • Stanton (St) • Stokes (Stk) • Strouhal (St) • Stuart (St) / (N) • Suratman (Su) • Taylor (Ta) • Thring (Th) • Ursell (U) • Weber (We) • Weissenberg (Wi) • Womersley (α) / (Wo) • Zwietering (S)

Vegeu també: Magnitud adimensional • Teorema de Pi-Buckingham

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