传导-对流型热流的计算模拟

MATHEMATICAL SIMULATION OF HEAT FLOW OF CONDUCTIVE-CONVECTIVE TYPE

本文对8个初始模型和7个组合模型中沿断层的水热对流、断层产状、山体地形和沉积盆地与基岩热导率反差等四个影响因素对传导型地表热流分布的影响进行了计算机模拟研究。模型设计和参数的选值以西藏中北部一些地热区实测的传导-对流型热流为主要参考依据,但不直接涉及对流组分的校正,而着眼于更广泛的单因子和多因素的模型研究。分析中采用无量纲参数:α=(K_1)/(K_2)(K_1和K_2分别为基岩和沉积盆地的热导率),β=(q_1)/(q_2)(q_1和q_2分别为地表热流的垂向分量和模型的底部热流)以及γ=L/H(L和H分别为离模型左侧边界的距离和山体的高度),以求更广的普适性。对模拟结果的分析表明,上述四项影响因素依其重要性可排序为对流强度—断层倾角—介质热导率反差—地形效应。

In this paper the results of computer simulation of the effect of hydrothermal convection along faults, as well as the occurrences of faults, mountain relief and contrast in thermal conductivity of sedimantery basin and basement rocks as four major conditioning factors on the distribution of conductive surface heat flow in eight original and seven combined models are reported. The model designing and parameter selection are mainly based on the observed surface heat flow of conductive-convective type in some geothermal areas in the North-Central Tibet. However, the correction for convective component is not directly involved here, instead, a much profounder single-factor and multifactor model investigation is implemented. In order to reach better applicability of the simulation results a series of dimensionless parameters such as α = K1/K2 (where K1 and K2 stand for thermal conductivities of basement rocks and sedimentary basin, respectively), β = qy/q (where qy and q signify the vertical component of surf ace heat flow and basal heat flux at the bottom of the model, respectively), and r = L/H (where L and H are the distance from the left boundary of the model and height of the mountain, respectively) are adopted. The analysis of the simulation results shows that in the light of their importance the above-mentioned four factors can be arranged in the following order: convection velocity-occurrences of faults-contrast in thermal conductivities of medium-topogrphic effect.