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Recent observations in extreme-ultraviolet (EUV) wavelengths reveal an EUVlate phase in some solar flares that is characterized by a second peak in warmcoronal emissions ($\sim3$~MK) several tens of minutes to a few hours after thesoft X-ray (SXR) peak. Using the model enthalpy-based thermal evolution ofloops (EBTEL), in this paper we numerically probe the production of EUVlate-phase solar flares. Starting from two main mechanisms of producing the EUVlate phase, i.e., long-lasting cooling and secondary heating, we carry out twogroups of numerical experiments to study the effects of these two processes onthe emission characteristics in late-phase loops. In either of the twoprocesses an EUV late-phase solar flare that conforms to the observationalcriteria can be numerically synthesized. However, the underlying hydrodynamicand thermodynamic evolutions in late-phase loops are different between the twosynthetic flare cases. The late-phase peak due to a long-lasting coolingprocess always occurs during the radiative cooling phase, while that powered bya secondary heating is more likely to take place in the conductive coolingphase. We then propose a new method for diagnosing the two mechanisms based onthe shape of EUV late-phase light curves. Moreover, from the partition ofenergy input, we discuss why most solar flares are not EUV late flares.Finally, by addressing some other factors that may potentially affect the loopemissions, we also discuss why the EUV late phase is mainly observed in warmcoronal emissions.

Probing the Production of Extreme-ultraviolet Late-Phase Solar Flares by Using the Model Enthalpy-Based Thermal Evolution of Loops