The structure and the thermodynamics of the non-magnetic boundary layer (BL) of accretion disks has been an outstanding problem in the field of theoretical astrophysics for years. The BL is a ubiquitous phenomenon that appears in a variety of astrophysical situations and systems where non-magnetic accretion occurs, i.e. where an accretion disk (AD) is present. The AD is an efficient mechanism to transport matter from the exterior of the disk to the gravitating center. Here, at the inner edge of the AD, the circulating matter comes upon the surface of the central object and is decelerated to match the object’s rotation rate. During this process, an enormous amount of energy is released from the tiny BL region. This in turn generates hard radiation which can be clearly identified in the observed spectrum of the object. We perform numerical hydrodynamical simulations in order to calculate the luminosity and the spectrum of the BL and its dependence on parameters like the mass, rotation rate or mass accretion rate of the central white dwarf (WD). Therefore, we treat the problem in the one-dimensional, radial slim disk approximation. We employ a classical α-viscosity to account for the turbulence and include cooling from the disk surfaces as well as radial radiation transport. To account for the high temperatures in BLs around WDs, we also consider the radiation energy in a one-temperature approximation. We find that 1D models of the BL are well suited if one is interested in the radiation characteristics of the BL. The BL luminosity directly depends on the varied parameters which makes it possible to draw conclusions about real systems by comparing observations with our synthetic models. Ambiguities concerning different models with identical luminosities can be mitigated by regarding the emitted spectrum. We therefore present a method to gain information about a system by probing the radiation of the BL.