Hidrológiai Közlöny 1967 (47. évfolyam)

4. szám - Egyesületi és műszaki hírek

226 Hidrológiai Közlöny 1967. 4. sz. Bogárdi J.: Kapcsolatok elméleti vizsgálata CyTb HOBoro MeTo/ia, H3Jio>KeHHoio B AaHHoií CTaTbe COCTOHT B TÓM, HTO HBJieHHe B HailieM CJIYMae ABH>KeHHe HaHOCOB COCTOHT H3 pa3MepHbIX H Ge3pa3MepHbIX (j)H3HMeCKHX xojiHiecTB, KOTopbie oöpasyioT noTeHnnaJibHbie ilHHa.MHqeCKHe CKOpOCTH. rioTeHunajibHbie AHHAMHIECKHE CKOPOCTH BEPOATHO He OflHHaKOBbie C (JjaKTIMeCKHMH CKOpOCTHMH, a TOJlbKO SIBJIfllOTOI Tai< Ha3bIBaeMbIMH ,,BO3M0>KHbIMH" CKOpOCTHMH. HYWHO ynoMjiHvrb, MTO HOBBIÍÍ cnocoö He orpammHaeTCH AJT5I eflHHCTBenHoro ripiiMeHemiH noTeHUHajibHbix c KopocTeíí. B npHHunne jiio6a>i pa3MepHan BejiHiHHa MO)KeT 6bITb CHIlTaTbCH nOTeHIUiaJTbHbIM 3HaMeHHeM H MOweT őbiTb iicn0Jib30BaHa K onpe/iejieHiiio CBH3en, i<aK H c KOpOCTH. B KaiecTBe npiiMepa MOPYT őbirb BBeaenu noTeHUnaJibHbie HHHaMimecKiie ycKopennn, HJHI noTeHnnaJibHbie AHHaMimecKHe AJIHHM. B HeK0T0pwx cjiynaax na>Ke BbiTOAHO BBeaeHHe noTeHnnajibHbix ycKopemiii, noCKOJlbKO HX MO>KHO CHHTaTb KaK nOTeHUHaJIl.Hbie yCHJlHfl, iieiícTByiouiHe Ha eflHHHUbi Macc. OflHaKO 5ICHO, MTO B OÖJiaCTH ABH>KeHH}I HaHOCOB ncii0Jib30BaHne noTemuiajibHbix CKopocreií oöecneiHT HanGojibuioe KOJiH^ecTBO npen.wymecTB H noaroMy B flaHHOÍÍ CTaTbe i— 3a HCKJiKmeHHeM HeKOTopbix ripmiepoB — ncnoJib3yioTC5J JiMinb noTeHHnajifaHbie CKopocrii. nocKOJibi<o H noTeHmiajibHbie AHHaMHHecKiie CKOpOCTH, H yCKOpeHHfl HaXOAHTCa B CBJ13H C I13BeCTHblMH <íe3pa3MepHbIMH HHCJiaMH, TO OTflejlbHO nOKa3bIBaiOTCH CBH3H nOTeHUHaJIbHHX aHHaMHMeCKHX CKOpOCTeH. XOTH noTeHUHaJibHbie CKOPOCTH, ycKopeHHji HAJIMHU luiJiyCTpnpyioTCH npHMepaMH, AJIH nojiHOTbi B 0T/i,e;n.H0Íi rjiaBe 3aHH,\iaeMCfl c pa3peineHneM Hei<0T0pbix TeopeTHMecKiix CBHsefi npH no.womn aaHHoro MeToaa. TaKiiM 06pa30M aaHHan CTaTbH noKa3biBaer reopeTHMeCKyiO CBH3b CpeAHeH CKOpOCTH OAHOrO HaHOCHOrO BOAOTOKa, a Tai<>Ke onpeAeneHiie napa.MeTpa, npuroaHoro jyifl paciéra BJieKOMbix HaHOCOB, pacneT KpHTHMecKoii CKOPOCTH, fleíícTByroiueH npn nepexo/IHOM COCTOAHHH ABH>KeHHfl-n0K0H h HaKOHeu BBeaeHHe TeopeTniecKon CBH3H CKopocTefí ocawAeHHfl. Theoretical eonsiderations on relationships describing sediment Iransportation By Dr. Bogárdi, J. Corresponding Member of the Hungáriái) Academy of Sciences As is well known from the literature an extremelv 1 arge number of relationships has been suggested for describing sediment transportation phenomena. Somé of these have been derived on the hasis of theoretical tjonsiderations, while somé are based on a fairly tight correlation established for a particular set of observation conditions. Aside from these further expressions are known which have been derived using a theoretical approach and verified by experiments subsequently. Practieal problems cannot be solved unless reliable relationships of reasonable accuracy are available. For this reason a eriticai review of almost every relationship published and commonly used has been found necessary. \ The first step in this review consists of clearing the theoratical fundamentals, the formai composition and structure of the relationships. In order to do so a new method is introduced in the present paper for deterinining relationships. A mathematical guarantee is offered by the method that only independent variables should be included in the relationships. The new method consists essentially of the introduction of potential dynamic velocities which can be förmed of the dimensional and dimensionless quantities describing the phenomenon, i. e. in this particular case sediment transportation. Potential dynamie velocities are obviously not identical with actual velocities, but only sueh which may oecur. It should be noted that the new method is not restricted to the application of potential velocities exclusively. In principle, any dimensional quantity could be regarded as a potential quantity, and may be used for the determination of relationships just as well as velocities. Thus for instance potential dynamic accelerations, or potential dynamic lengths could be introduced. In certain instances even benefits may accrue from using e. g. potential dynamic accelerations, which may be regarded as potential forces acting on unit mass. In sediment transportation, however, the use of potential velocities is most practicable, and for this reason with a few exceptions these will only be used in the present paper. In view of the fact that both potential dynamic velocities and accelerations are related to known dimensionless numbers, these relationships are given separately in the paper. Although the introduction of potential velocities, accelerations and lengths is always illustrated by examples, a separate chapter has been devoted to the determination of Somé of the more familiar relationships by the method suggested. A theoretical relationship is thus derived for the mean velocity of a sediment carrying watercourSe, the determination of a parameter Suitable for calculating bed load is deScribed, the critical shear velocity at the boundarv condition of incipient movement is calculated and a theoretical relationship for fali velocity is derived. J