Asymptotic solution for 3D Lee waves across Assam-Burma hills

Abstract

bl 'kks/k i= esa vle cekZ dh igkfM+;ksa ¼,ch,p½ ds Åij ls cgus okyh yh osc ds m/oZokg@v|ksizokg ds ekSfyd cgko dks vkn’kZ :i  esa izLrqr djus ds fy, ,d mixkeh fu"d"kZ izkIr djus dk iz;kl fd;k x;k gS tgk¡ LFkf;Ro vkSj iou dk ekSfyd cgko Å¡pkbZ ds lkFk fu’pj jgrs gSaA vle–cekZ igkfM+;ksa ds lfUudV nks f=vk;keh nh?kZo`Urkdkj jksf/kdkvksa ds }kjk ig¡pk x;k gS tks dqN fuf’pr nwjh ij ,d ?kkVh }kjk foyx gSA bldks lgtrk ls le>us ds fy, iou ds ekSfyd cgko dks jksf/kdkvksa ds cM+s&cM+s fdukjksa ds yacor ,d vo;o ekuk x;k gSA blds fy, xofuZax lehdj.k esa {kksHk rduhd dks ykxw fd;k x;k gSA {kksHk mnxz osx ¼½ vkSj ok;q izokgh js[kk dh nwjh ¼½ dks f}’k% lekdyksa esa n’kkZ;k x;k gS ftls mixkeh foLrkj ds :i esa le>us dk iz;kl fd;k x;k gSA blls izkIr ifj.kke lqlaxr ik, x, gS vkSj bldh rqyuk iwoZorhZ vUos"k.k dRrkZvksa }kjk izkIr fd, x, ifj.kkeksa ls dh xbZ gSA

 An attempt has been made to obtain an asymptotic solution for the updraft/downdraft associated with Lee wave across the Assam-Burma hills (ABH) for an idealized basic flow, where, both stability and wind in the basic flow remain invariant with height. ABH has been approximated by two three dimensional elliptical barriers, separated by a valley of some finite distance. For simplicity, the basic flow has been assumed to have only one component normal to the major ridges of the barriers. For this purpose, perturbation technique has been applied to the governing equations. The perturbation vertical velocity () and streamline displacement () are expressed as double integrals, which have been attempted to approximate as an asymptotic expansion. The results obtained are found to be consistent and have been compared with the results obtained by earlier investigators.