1. O.nly within the last decade, with tile advent of l;irge, high-speed digital c0tnp 11ters, has the pi·ohlem of numerical intcgt'ation of the two-dimension:11 cornp 1'cssible turbulent boundary- layer equations using a two-laycl' (inner-outed eddy viscosity n1ndcl to describe turbulence bccom, feasible, The works of Smith wcl Cd)cci, ( l) P.'.ltnnkti.r and Sp:ildi.n1; (2} ,nd Hr,rring and Mr.,1101·,(·1) ,1s well as the I,m,gley C:ornpn·ssiblc Turbulent Hournbry Layer Symposium, (•1) arc rcprc;Hmtative cxamplc,s of the current cstale-of-the-<'lrt in numerical calculation techniques for compressible two-dimensional lurbulcn 1 boundary- layer flow; In general, the two-layC'r (inner-o,iter) eddy viscosity law, coupled with the so-called v:i.n Driest damping for the ncai'-w,11 region, nppcnrs t0 be cnLirely satisfactory and ;J.Ccurate for two-climcnsion:il turbulent boundary-layer flows in the subsonic and s upc rsonic regime. J\forc recent work, (5-9) indicate that the s:unc two-layer eddy viscoc;ity law is ar,plicabl c even in the hypcesonic regime.
2. a. The rates of change of the mean flow properties in the x- and · directions r C(1): arc smaller than the i·atcs of change in the y-dircction [{ 1(6-1): by an order of magnitude, ·
3. where R 1716 ft 2/sec'.L 0 R. Hence, under this assumption, h = CT p