Numerical analysis for jet flow field on cleaning the outer wall of the double-layer injection needle

Abstract To avoid cross-contamination between different samples, improve the cleaning effect of outer wall inner needle digital PCR detector, and reduce cost solution, jet was simulated by FLUENT software using VOF gas-liquid two-phase flow model PISO algorithm. In a certain range, inlet velocity, solution viscosity, interfacial tension, contact angle are changed to simulate theoretical injection probe selection various parameters under best conditions is determined. The results show that increase velocity has no significant on static pressure decrease increases; viscosity will greatly rate; higher tension requires form continuous jet; increasing not significantly rate, residual sample easier clean. When 200mm /s selected, fluorine oil with 0.00124Paꞏs 16.2dyn/cm used coated Teflon, effect, economy excellent.