A phase-field model (PFM) coupling with phase field, flow field and diffuse equation is presented for simulating isothermal dendrite growth of a nickel-copper alloy under a forced flow. Based on the finite difference method with uniform grid, the C programming code is implemented to complete the phase-field simulations. The simulation results indicate that the interfacial morphology, the symmetry of dendrite formation, the tip growth velocity and the concentration distribution are strongly influenced by the fluid flow. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.