FLOW-3D v10.1.1 + FLOW-3D CAST Advanced v3.5.2 + Full Crack
continuous foam flow was observed in all cracks with different wall roughness (see fig. 2 ). the results of flow rate and pressure gradient are plotted in fig. 13. generally, foam flow rate increased with increasing flow rate and crack roughness. it was found that foam flow rate reached a maximum for cracks with roughness of about 3.5 μm and the flow rate decreased again with crack roughness becoming higher than 4.5 μm. the reason for this behavior might be that the foam film in cracks with roughness of 4.5 μm was too large to be stabilized by the very stable gas-liquid interface, as shown in fig. 12. with the addition of nanoparticles, the pressure gradient significantly increased with increasing foam quality, no matter whether the nanoparticles were adsorbed at the gas-liquid interface or inside the foam network. figure 13 shows that the pressure gradient was significantly higher for cracks with 1.00wt% sio2 nanoparticles than cracks without nanoparticles at foam quality of 92% and 98%. for cracks with sio2 nanoparticles, more sio2 nanoparticles were adsorbed on the gas-liquid interface, which could be thermodynamically stable due to the adsorption of sio2 nanoparticles and the formation of hydrogen bonds between the sio2 nanoparticles and the water molecules. therefore, more sio2 nanoparticles were adsorbed at the gas-liquid interface than in the foam network, resulting in higher pressure gradient and foam flow rate. in comparison to cracks without nanoparticles, cracks with nanoparticles adsorbed on the gas-liquid interface or inside the foam network could reach the same foam flow rate for foam qualities lower than 92% and 98%. for cracks with nanoparticles, as foam quality was increasing, the pressure gradient gradually decreased even to foam qualities lower than 92%. at foam qualities lower than 92%, the pressure gradient can reach the maximum for cracks without nanoparticles, which increased the flow rate. for cracks with nanoparticles adsorbed at the gas-liquid interface, with foam quality continuously increasing, the surface of bubbles was gradually covered by nanoparticles. as a result, less gas channel and foam film were formed leading to flow rate decrease. for cracks with nanoparticles adsorbed inside the foam network, for foam quality lower than 92%, the foam was still very stable and the gas channel was not blocked by nanoparticles. therefore, the foam film was very stable and the flow rate increased slowly with foam quality. at foam quality higher than 92%, the foam was very unstable and gas channels formed leading to foam flow rate decrease.
flow 3d v10 crack 12