NUMERICAL STUDY OF THE MESH RESOLUTION EFFECT ON STRATIFIED GAS-LIQUID FLOW IN PIPES Dr. Esam M. Abed and Zainab K. Ghoben Department of Mechanical Engineering, Babylon University, Iraq. Abstract The hydrodynamic behavior of two-phase gas-liquid stratified flow in long horizontal pipes was numerically simulated. The simulation carried out with computational fluid dynamics CFD software FLUENT and the Volume of Fluid VOF model. The geometry represented by 25.4 mm diameter and 6 m length pipe, the mesh has been accomplished by using the industrial level mesh generation tool Gambit. The effect of mesh resolution on the stratification process was discussed. Simulation results show that mesh structure plays a dominant role in the separation of the two phases and speeding up the appearance of waves to form wavy stratified flow later. Two types of cell structure examined here which are simple cylinder mesh and O-grid mesh and discovered that the O-grid mesh type is the best. This study to be available; a clear comparison of the stratified flow pressure drop phenomenon with other experimental studies are accomplished and getting an agreement in this field. ϥΎϳήجϟ اϰϠ عΕΎϤϴقسΘϟ اΔϜΒ شΔقΩϭ ϞϜ شήϴأثΗ ضحϮΗ ΔϳΩΪ عΔاسέΩ ίΎ غέϮτϟ اϲئΎϨ ث– ΐϴΑΎϧا اϲ فϞئΎ سΔϴافق ا لخاصة ا ίΎ غϱέϮτϟ έϮτϟ اϲئΎϨ ثϞفصϨϤϟ اϥΎϳήجϠϟ ΔϳΩΪ عΔجάϤϧ ϞϤ عϢΗ - ϥΎϳήجϟ اϝ خاϦϴئعΎϤϟ اϩάΨΘϴ سϱάϟف اήصΘϟ اΔاسέΪϟ ϞئΎ س, Εΰجϧ أ ΔϴΑΎحسϟائع اϮϤϟ اΔϴϜϴϣΎϨϳΩ ϢϠ عϡاΪΨΘسΎΑ ΔϳΩΪعϟ اΓΎكΎحϤϟ ا) CFD ) ΖϧϮϠج فϣΎϧήΑ ϲ ف) FLUENT ) ئعΎϤϟ اϢ حجΔϳήظϧ قϴΒτΗ ϢΗϭ ) VOF ,) ήτقΑ عτقϤϟ اϱήائΩ ΏϮΒϧأΑ ϢجسϤϟ اϞثϤΘϳ 25.4 ϝϮρϭ ϢϠϣ 6 ϡ , ΖΒϣΎ ججϣΎϧήΑ ϡاΪΨΘسΎΑ ΏϮΒϧأϟ ΕΎϤϴقسΘϟ اΔϜΒ شϞϤ عϢΗ ) Gambit .) ϦϴئعΎϤϟ اϞ فصϰϠ عΕΎϤϴقسΘϟ اΔقΩ ήϴأثΗ ϯΪϣ ΔاسέΩ ϢΗ Ϊقϟ . Ϟفصϟ اΔϴϠϤ عϲ فϲسϴئέ έϭΩ ΕΎϤϴقسΘϟ اΐϴكήΗϭ ϞϜشϟ ϥ اΔجάϤϨϟ اϩά هϦج عΘϧ ΪعΑ ΎϤϴ فαΎϤΘϟ اΔقτϨϣ ϲ فΕΎجϮϤϟ اέϮϬع ضϳήسΗ ϭ . ΔϜΒ شϭ ΔτϴسΑ ΔϴϧاϮτ اسΔϜΒ شΎϤ هΔϤϴقسΘϟ اΐϴكήΗ ϭء اΎϨΑ ϲ فϦϳأΪΒϣ ΔاسέΩ ϢΗ فήحϟ ا) O ) فήحϟ اΔϜΒ شϥشف اΘاكϭ ) O ) Ϟπاف اϲ ه. ϝϮ حΔقΑΎ سΔϴϠϤ عΕΎاسέΩ عϣ ΔϧέΎقϣ ϞϤ عϢΗ ϯϭΪ جΕاΫ ΔاسέΪϟ اϩά هϞجعϟ ήϴΒافق كϮΗ Ϊجϭ Ϊقϭ έϮτϟ اϲئΎϨ ثϥΎϳήجϟ اϲ فςغπϟ اρϮΒ هΓήهΎυ . Nomenclature h L , liquid level in pipe. ϴ, is the pipe inclination angle which is 0 in horizontal pipes. β, liquid level angle. D, pipe diameter. α L , liquid fraction. p  , frictional pressure drop.  , two-phase pressure drop multiplier.  , density. u, velocity.