这句英文该如何改写？

　　这句英文该如何改写？。In DSMC simulation, the calculation domain is divided into cells, and which cell every molecule is located in must be calculated at each time step.
中文意思是: 在做直接模拟蒙特卡罗（DSMC）模拟时，计算区域被划分成网格单元（Cells），每一计算步里，每个置于哪个网格单元需要计算。
让二个同学看过了，都说看不懂，如何改写？先谢过大家了。
===有问必答===
In the DSMC simulation, the computational region is divided into grid cells, andevery molecule in which grid unit needs to be calculated at each step.