Abstract A simple method is described for calculating distances from walls in circumstances of complex geometry. This is then used as the basis of a comparative study of conjugate heat transfer, involving two previously published and one new low-Reynolds-number turbulence models. It is argued that the new model, called LVEL, performs as well as the older Lam-Bremhorst-Yap and Two-Layer-κ-ε models. Since it is computationally less expensive, and easily applied to three-dimensional problems, it is recommended for practical use, especially for electronics-cooling applications.