1.515+0.076 1.61 H Ct -.067+0.0197(7.4-8k) 成k<7.4 067+0.022 >7.4 H 0.26 0.207+0.00205(4-Hk 4 D 0.207 0.22 0.003(Hk-4) Closure relations-tvD-eguatiom, lami or, integra/ metho one equation (Thwaites) .------.two equation finite difference arious BL calculation metheds