The velocity profiles of unsteady Couette flow at t = 1.00 × 10⁻³ s: (a) low collision number; (b) high collision number. The symbols ■, ▲, ⋆, • and ♦ are the results of case 1, case 2, case 3, case 4 and case 5, respectively. Under low collision number in (a), the models agree well with each other, and share a similar profile with the analytical solution. Under high collision number in (b), ECD stays consistent with the analytical solution while SA fails. The detailed descriptions of cases are listed in Table 1.