This is how ultra filtration carried out in the glomerulous.
Hydrostatic pressure is increased by making the lumen of the afferent arteriole more and narrowing the lumen of the efferent arteriole . So clearly as the blood gushes in from the renal artery and when spread over a wide web of fine capillaries and the exit blood vessel being made deliberately narrow, it creates a huge hydrostatic pressure on the glomerulus forcing ultrafiltration of the blood to take place.