Tokyo Institute of Technology · Engineering
Professor Chunwei Zhang's research lab specializes in pore-scale multiphase flow and solute transport in porous media, with a strong emphasis on understanding fundamental mechanisms governing fluid displacement, dispersion, and trapping in geologic and engineered systems. Using advanced imaging techniques such as micro-focus X-ray computed tomography and numerical simulations like the lattice Boltzmann method, the lab investigates phenomena including capillary trapping, snap-off dynamics, and non-Fickian dispersion under varying wettability, capillary numbers, and flow conditions. The work bridges microscale physics with macroscale transport behavior, with direct applications in carbon dioxide sequestration, enhanced oil recovery, and subsurface environmental remediation.
Figures are computed from collected data and may differ slightly.
Solute transport in porous media is sensitive to heterogeneity at all scales. However, the pore-scale solute transport behavior may considerably affect the behavior at larger scales. Here, a multi-relaxation-time lattice Boltzmann method with Flekkøy's mass transfer scheme is employed for simulating the fluid flow and solute transport in three-dimensional porous media obtained from high-resolution micro focus x-ray computed tomography, namely, randomly packed glass beads and four consolidated sa
With the aid of nondestructive microfocus x-ray computed tomography (CT), we performed three-dimensional (3D) tracer dispersion experiments on randomly unconsolidated packed beds. Plumes of nonreactive sodium iodide solution were point injected into a sodium chloride solvent as a tracer for the evaluation of the dispersion process. The asymptotic dispersion coefficient was obtainable within the experimental scale and was summarized over Péclet numbers from 11.7 to ∼860. Then, the lattice Boltzma
Snap-off usually occurs during two-phase fluid displacement in a constricted capillary, where the nonwetting phase fluid is cut into blobs or ganglia due to surface tension. Snap-off has been intensely recognized as a predominant pore-scale mechanism that may be responsible for the breakup and trapping of the nonwetting phase in complex geophysical structures. Herein, we investigated the dynamics of snap-off in a constricted pore and throat structure with a square cross-section using the volume
Solute transport through variably saturated porous media is ubiquitous in multiple subsurface flows, piquing the geoscience community's interest. This study adopts a novel experimental approach using microfocus x-ray computed tomography for real-time imaging of a three-dimensional NaI tracer plume in a partially saturated packing column. A stabilized two-phase flow field is achievable through continuous co-injection of two-phase fluids: NaCl solvent and pump oil. Thus, the critical role of the N
Capillary trapping of the non-wetting phase in porous media is vital for long-term CO2 sequestration and underground gas storage. While injection strategies have received extensive research attention, the pore-scale mechanisms controlling residual gas stability during wetting phase re-imbibition under varying injection directions coupled with buoyancy remain unclear. This study used high-resolution micro-focus X-ray computed microtomography imaging and quantitative analysis to investigate gas tr
多孔質中の非混和二相流に関する現象はCO2地下貯留や原油増進回収，土壌修復など様々な工業的，自然科学的応用を有している。ハイネスジャンプや毛管圧浸透などの空隙スケールの現象は置換プロセスに大きな影響を与えることが知られている。ハイネスジャンプは周囲の空隙内におけるメニスカスの再配置を伴いながら二相界面が急激に移動する現象である。対して，毛管圧浸透は濡れにくい相が大きな空隙を平坦な界面を維持しながら選択的に浸透する現象である。本研究では，様々なスロート径を有するランダムな構造を有する多孔質における排水過程の数値シミュレーションを行った。ハイネスジャンプと毛管圧浸透は飽和率の変化に影響を与える。ハイネスジャンプでは飽和率が変わらず先端界面の移動が生じる。一方，毛管圧浸透では先端位置がほとんど変化せず，飽和率の上昇が発生する。さらに，キャピラリー数と粘性比の影響を調べた。高いキャピラリー数と高い粘性比が，CO2などの濡れにくい相のキャピラリートラップには有効である。エネルギー収支を求めた結果，外からなされた仕事の48%がこれらの不可逆過程で散逸していることが分かった。
Snap-off usually occurs during two-phase fluid displacement in a constricted capillary, where the nonwetting phase fluid is cut into blobs or ganglia due to surface tension. Snap-off has been intensely recognized as a predominant pore-scale mechanism that may be responsible for the breakup and trapping of the nonwetting phase in complex geophysical structures. Herein, we investigated the dynamics of snap-off in a constricted pore and throat structure with a square cross-section using the volume
Snap-off usually occurs during two-phase fluid displacement in a constricted capillary, where the nonwetting phase fluid is cut into blobs or ganglia due to surface tension. Snap-off has been intensely recognized as a predominant pore-scale mechanism that may be responsible for the breakup and trapping of the nonwetting phase in complex geophysical structures. Herein, we investigated the dynamics of snap-off in a constricted pore and throat structure with a square cross-section using the volume
Snap-off usually occurs during two-phase fluid displacement in a constricted capillary, where the nonwetting phase fluid is cut into blobs or ganglia due to surface tension. Snap-off has been intensely recognized as a predominant pore-scale mechanism that may be responsible for the breakup and trapping of the nonwetting phase in complex geophysical structures. Herein, we investigated the dynamics of snap-off in a constricted pore and throat structure with a square cross-section using the volume
From analyzing the current circumstances of the tourist market in Chongqing,this paper explains the basic conditions of the development for the tourist market in the resource basis of travel, developing basis of industries, and founding the basis of 'software' etc., and points out such negative factors for the tourist market in Chongqing as the advantages of tourist resources, size and strength of tourist enterprises, the whole quality of the employees, tourist publicity sale, tourist backup, in
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