Underbody and ground effects on rotating disc flow: a global scale inviscid study

The flow induced by a finite disc rotating near horizontal ground is considered, including the effects of an underbody. This paper concentrates on determining the shape of the free layer beyond the rim of the disc which is horizontal in the absence of the underbody and ground but forced to deform to ensure that conditions across the layer are satisfied when the underbody or ground is added. The far-field behaviour, the inviscid flow produced by a nominally infinite disc near the ground and the global solution for small ground clearances are considered analytically, and the full problem is posed as an integral problem. This is then solved numerically and analytically. Results are presented for various heights of the disc above the ground and for discs with an axisymmetric underbody present. A universal form is found for the farfield shape (which is controlled by entrainment into the free layer) but both the underbody and the ground effects are found to increase very significantly for reduced clearances.     

The cyclodimerisation of 3-methyl-2-butenenitrile

3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3).     

Preparation of some perhydrothiazolo[3,2-a] [1,3,5] triazine-2,4-diones

2-Dialkylamino-δ²-thiazolines were found to react with aryl isocyanates to give 1,3-diaryl-8a-dialkylaminoperhydrothiazolo[3,2-a ] [ 1,3,5]triazine-2,4-diones (IIa-c), while p-toluenesulphonyl isocyanate gave a 1:1 adduct (VII). No reaction was observed with alkyl or aryl isothiocyanates.     

The nonlinear shear gradient effect on the shear viscosity of a ternary system near a plait point

We have studied the shear viscosity of a ternary liquid mixture (water-ethanol-chloroform) near a plait point by the capillary method and found an apparently strong levelling-off as we approach the critical point. This levelling-off cannot be explained simply in terms of a strong cusp. It is found that the nonlinear shear gradient effect suggested by Oxtoby can be used to explain this behavior.     

Comparison of MBPT and coupled-cluster methods with full CI. Importance of triplet excitation and infinite summations

Results from full fourth-order perturbation theory [SDTQ MBPT(4)], and the coupled-cluster single- and double-excitation model (CCSD). are compared with recent full CI results for BH, HF, NH₃, and H₂O. For H₂O, studies include large symmetric displacements of the OH bonds, which offer a severe test for any single-reference MBPT/CC method. In every case. CCSD plus fourth-order triple-excitation terms provide agreement with the full CI to < 2 kcal/mole. SDTQ MBPT(4) has an error 10 kcal/mole for displaced H₂O.     

Studies on the chemistry of 2,3,5,6-tetrahydro-6-phenylimidazo[2,l-b]-thiazole. III. . Reaction with isocyanates and isothiocyanates

2,3,5,6-Tetrahydro-b-phenylimidazo[2,l-b-]thiazole reacts with aryl isothiocyanates to give dipolar 1:1 adducts. The adducts are relatively unstable and, in solution, exist in equilibrium with starting materials. The reaction with aryl and alkyl isocyanates, however, leads to cyclic 2:1 adducts, while sulphonyl and acyl isocyanates give stable dipolar 1:1 adducts. J. Chem. Soc., 14, 989 (1977)     

The regiochemistry and stereochemistry of 1,3-dipolar cycloadditions of 1-fluoro- and 1,1-difluoroallene

1,3-Dipolar cycloadditions of diazoalkanes, nitrones and nitrileoxides occur with high regioselectivity to 1,1-difluoroallene and fluoroallene, and with variable syn or anti π-facial diastereoselectivity with regard to additions to the latter. The roles of steric effects, frontier molecular orbital effects, electrostatic interactions and other factors which may be involved in determining the observed regioselectivity and π-facial diastereoselectivity are discussed.