Muaj ntau hom tawv nqaij uas muaj cov yam ntxwv sib txawv thiab SIV: Piv txwv li, cov tawv nyuj tawv zoo yog qhov zoo siab uas yog qhov tsim nyog tshaj plaws rau cov tawv ntoo ntawm cov tawv nqaij; Yaj tawv yog lub teeb, nyias thiab muag uas yog lub zoo tagnrho cov ntaub rau tawv khaub ncaws; Npua tawv tau zoo dua cov pa permeability thiab dej paug permeability. Tus npoo tawv: qhov pore ntawm tawv tawv yog hloov thiab loj heev uas yog inclined ntev rau hauv tawv tawv.Qhov kev kho ntawm pore yog 3 nyob rau hauv ib pawg, tawv lub ntsej muag nthuav dav tus tsim ntawm ntau daim duab peb sab.
Cow tawv: ob qho tib si nyuj thiab twm tawv tawv yog hu ua nyuj tawv, tab sis muaj qee qhov sib txawv.Qhov pores nyob rau saum npoo ntawm cov nyuj tawv yog hloov thiab ntev rau hauv cov tawv ncaj.Tus pores ntawm cov tawv twm tawv yog loj dua cov nyug tawv, cov pores muaj tsawg dua li ntawm cov tawv nyuj, thiab tawv zoo yog qhov ntau so, tsis yog li muag thiab plump raws li ntawm cov tawv nyuj.
Nees tawv: Cov plaub hau ntawm tawv tawv kuj qhia tau hais tias ellipse uas loj dua li cov tawv nqaij ntawm cov tawv nqaij, npaj kev cai ntxiv.
Yaj tawv: qhov pore ntawm tawv ntse ntse yog oblate thiab cov pore yog tseeb. Ob peb qho chaw nres nkoj ua ke pawg ib pawg twg yog qhia tias ntses nplai.