In the recent years, using electric arc furnaces for steel making had an salient increase. Vast utilization of electric energy for metal melting instead of old fuels shows an necessity in investigating in this field. Direct current electric arc furnaces are kind of steelmaking equipments which have more benefits in different industries comparing with alternative current electric arc furnaces and consequently using them is in growth in industry. Metal refining stage in steel making process is so significant because in this stage molten bath heating, in a steady state process, will resume until the melt under influence of heat and jet momentum which conducted by electric arc, become more homogenized and distribution of temperature field become smoother. Effective parameters in bath mixing in direct current electric arc furnace can be counted as : buoyancy force , Lorentz force and momentum jet of direct current electric arc. Effect of each one of these parameters in bath circulation is investigated and by a simultaneously solving of momentum, energy and electromagnetic equation in Fluent with auxiliary module of magneto hydro dynamics and writing specific codes in Fluent for introducing electromagnetic force and distribution of heat flux and shear stress which knows as “ User Defined Function (UDF)” ,fluid flow pattern will be recognized. This pattern shows that near the furnace axis, molten bath has a counter clockwise motion which happens under the influence of electromagnetic force and current density distribution close to axis. At the points close to side walls of furnace, due to the reduction in electromagnetic field effect and domination of buoyancy force, bath circulation is changed and shows a clockwise circulation. There is lots of parameters such as total amperage of arc, electric arc length and foamy slag practice which affect on bath mixing phenomena and temperature field. Changing amount of total amperage in a constant length of arc, from 36 KA to 40, 44 and 50 KA shows that, values of average temperature increase. This happens because of growth in amount of energy transferred to molten bath and flow pattern face with changes in 40KA and 25cm arc length comparing with 36KA. This is because of increasing in current density passing through the bath causing electromagnetic force dominate in bath circulation and buoyancy effect lessen in bath circulation. Changing in electric arc length from 20cm to 25 and 30cm shows an increase in average temperature of melt.Comparing these results with other results in other research shows a good agreement. Slag effect impresses the average temperature of bath by increasing it about 30-35 degree which buoyancy effect was dominant. Key words: direct current electric arc furnace, bath circulation, electromagnetic,hydrodynamics
